ANDROID: power_supply: inline empty power_supply_get_by_phandle_array()

The static empty definition of power_supply_get_by_phandle_array(), used
when CONFIG_OF is not set, is missing an inline keyword. This generates
multiple compiler warnings and adds function-call overhead. This patch
inlines the definition to address such issues.

Fixes:
./include/linux/power_supply.h:405:12: warning: ‘power_supply_get_by_phandle_array’ defined but not used [-Wunused-function]
  405 | static int power_supply_get_by_phandle_array(struct device_node *np,
      |            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Bug: 183339614
Fixes: dea1a925 (ANDROID: power_supply: Add a helper function to retrieve psy array from phandle)
Reported-by: kernelci.org bot <bot@kernelci.org>
Signed-off-by: Carlos Llamas <cmllamas@google.com>
Change-Id: I6ad919673d0f649d7701c573196c11795663182d
(cherry picked from commit 1dccea76)