mfd: tqmx86: Refactor GPIO IRQ setup

Move IRQ setup into a helper function. The string "GPIO" for error
messages is replaced with a label argument to prepare for reusing the
function for the I2C IRQ.

No functional change intended.

Co-developed-by: Gregor Herburger <gregor.herburger@tq-group.com>
Signed-off-by: Gregor Herburger <gregor.herburger@tq-group.com>
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Link: https://lore.kernel.org/r/97f481334f480a113b7076e76f994e0e73ee5aa5.1731325758.git.matthias.schiffer@ew.tq-group.com


Signed-off-by: Lee Jones <lee@kernel.org>