drm/i915/psr: Fix using wrong mask in REG_FIELD_PREP

drm/i915/psr: Fix using wrong mask in REG_FIELD_PREP

Wrong mask is used in PORT_ALPM_LFPS_CTL_FIRST_LFPS_HALF_CYCLE_DURATION and
PORT_ALPM_LFPS_CTL_LAST_LFPS_HALF_CYCLE_DURATION.

Fixes: 295099580f04 ("drm/i915/psr: Add missing ALPM AUX-Less register definitions")
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Link: https://lore.kernel.org/r/20250526120512.1702815-12-jouni.hogander@intel.com
(cherry picked from commit 8097128a40ff378761034ec72cdbf6f46e466dc0)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>