gpio: palmas: fix implicit assumption module.h is present
This file is currently getting module.h from a global gpio header
and it will fail to build once we remove module.h from that.
However, the driver is controlled with the following Kconfig:
drivers/gpio/Kconfig:config GPIO_PALMAS
drivers/gpio/Kconfig: bool "TI PALMAS series PMICs GPIO"
and hence the line of MODULE_DEVICE_TABLE is a no-op that can simply
be deleted. In fact it should have been removed in an earlier commit
that did demodularization, however the unseen include prevented my
build testing from detecting it.