common: add GPIO controller function

The CPLD update process requires toggling a GPIO pin to control the
debug card mux. BIOS and EEPROM updates use the same logic, so refactor
the duplicated code i

common: add GPIO controller function

The CPLD update process requires toggling a GPIO pin to control the
debug card mux. BIOS and EEPROM updates use the same logic, so refactor
the duplicated code into a common GPIO controller function. Update BIOS,
EEPROM, and CPLD code paths to use the new helper.

Tested:
- Verified CPLD update with GPIO mux toggling
- Verified BIOS update with GPIO mux toggling

Verified CPLD update with GPIO mux toggling
```
Dec 18 18:33:35 bmc phosphor-cpld-software-update[1064]: Requesting chip gpiochip0, GPIO line debug-card-mux to 1
Dec 18 18:33:35 bmc phosphor-cpld-software-update[1064]: Updating Lattice CPLD firmware
Dec 18 18:33:45 bmc phosphor-cpld-software-update[1064]: [48K blob data]
Dec 18 18:34:14 bmc phosphor-cpld-software-update[1064]: [48K blob data]
Dec 18 18:34:31 bmc phosphor-cpld-software-update[1064]: Successfully updated CPLD
Dec 18 18:34:31 bmc phosphor-cpld-software-update[1064]: Requesting chip gpiochip0, GPIO line debug-card-mux to 0
```

Verified BIOS update with GPIO mux toggling
```
Dec 18 18:45:53 bmc phosphor-bios-software-update[1063]: Requesting chip gpiochip0, GPIO line FM_MUX1_SEL_R to 1
Dec 18 18:46:24 bmc phosphor-bios-software-update[2158]: [14.8K blob data]
Dec 18 18:46:30 bmc phosphor-bios-software-update[2158]: [47.9K blob data]
Dec 18 18:46:37 bmc phosphor-bios-software-update[2158]: [48K blob data]
Dec 18 18:46:44 bmc phosphor-bios-software-update[2158]: [48K blob data]
Dec 18 18:46:51 bmc phosphor-bios-software-update[2158]: [48K blob data]
Dec 18 18:46:58 bmc phosphor-bios-software-update[2158]: [47.9K blob data]
Dec 18 18:46:58 bmc phosphor-bios-software-update[2158]: [4.5K blob data]
Dec 18 18:47:01 bmc phosphor-bios-software-update[2158]: [48K blob data]
Dec 18 18:47:04 bmc phosphor-bios-software-update[2158]: [48K blob data]
Dec 18 18:47:07 bmc phosphor-bios-software-update[2158]: [48K blob data]
Dec 18 18:47:10 bmc phosphor-bios-software-update[2158]: [48K blob data]
Dec 18 18:47:13 bmc phosphor-bios-software-update[2158]: [48K blob data]
Dec 18 18:47:15 bmc phosphor-bios-software-update[2158]: [20.5K blob data]
Dec 18 18:47:17 bmc phosphor-bios-software-update[1063]: Successfully updated SPI flash
Dec 18 18:47:17 bmc phosphor-bios-software-update[1063]: Requesting chip gpiochip0, GPIO line FM_MUX1_SEL_R to 0
```

Change-Id: I8d3c128951fd833a0cd25e1440236f82d37b776f
Signed-off-by: Henry Wu <Henry_Wu@quantatw.com>

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