arch/x86/acpigen: Constify fieldlist parameter to acpigen_write_field

acpigen_write_field() does not need to modify the fieldlist
parameter. Thus, this change makes this parameter as const.

Change-Id: I94688913cee8948f42ae5e184f2d24264876648d
Signed-off-by: Furquan Shaikh <furquan@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40784
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/arch/x86/acpigen.c b/src/arch/x86/acpigen.c
index 82654e1..34de2ba 100644
--- a/src/arch/x86/acpigen.c
+++ b/src/arch/x86/acpigen.c
@@ -514,7 +514,7 @@
  *		PMCS,   2
  *	}
  */
-void acpigen_write_field(const char *name, struct fieldlist *l, size_t count,
+void acpigen_write_field(const char *name, const struct fieldlist *l, size_t count,
 			 uint8_t flags)
 {
 	uint16_t i;