wifi: iwlwifi: prepare for reading SPLC from UEFI

wifi: iwlwifi: prepare for reading SPLC from UEFI

As the iwl_bios_get_x() functions are now generated using a macro,
and this macro requires the all iwl_acpi_get_x() to have the same
prototype, change iwl_acpi_get_pwr_limit() to return a int
and the actuall power limit will be filled in a pointer function
parameter.

Signed-off-by: Miri Korenblit <miriam.rachel.korenblit@intel.com>
Reviewed-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://msgid.link/20240201155157.4cce81198afe.Ice8b1b97a68da9ec7b5a4799ddb668642198e1af@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>