drm/i915/alpm: Share alpm support checks with PSR code

Convert intel_alpm_aux_wake_supported and
intel_alpm_aux_less_wake_supported as non-static. Use them in intel_psr.c
instead of local variables.

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240607134917.1327574-8-jouni.hogander@intel.com