mb/system76/gaze15: Correct CMOS type for debug_level

When the century byte was reserved, the debug_level was accidentally
converted from an enum to a hidden value. Change it back to an enum.

Fixes: f05bd8830d ("mb/system76/*: cmos.layout: Reserve century byte")

Change-Id: Id88a7aed7b2fc793fd003db5b45f3f201b1a7630
Signed-off-by: Tim Crawford <tcrawford@system76.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57682
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jeremy Soller <jeremy@system76.com>

src/mainboard/system76/gaze15/cmos.layout

@@ -12,7 +12,7 @@ entries
 400	8	r	0	century
 
 409	2	e	7	power_on_after_fail
-412	4	h	6	debug_level
+412	4	e	6	debug_level
 984	16	h	0	check_sum
 
 enumerations