soc/amd/picasso: Move PMOD global variable to globalnvs.asl

Global variable `PMOD` that stores the interrupt mode used by OS is
required by all mainboards. This change moves the variable definition to
globalnvs.asl under picasso.

Additionally, ACPI spec says that BIOS should assume interrupt mode as PIC
until _PIC() method is called by OS. Thus, this change also updates the
default value of PMOD as 0 i.e. PIC mode.

BUG=b:153879530

Signed-off-by: Furquan Shaikh <furquan@google.com>
Change-Id: I731c03d965882281a7a23f55894451210ba72274
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43514
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/mainboard/amd/mandolin/acpi/mainboard.asl

@@ -12,4 +12,3 @@ Name(HPBA, 0xFED00000)	/* Base address of HPET table */
 /* Some global data */
 Name(OSVR, 3)	/* Assume nothing. WinXp = 1, Vista = 2, Linux = 3, WinCE = 4 */
 Name(OSV, Ones)	/* Assume nothing */
-Name(PMOD, One)	/* Assume APIC */

src/mainboard/google/zork/variants/baseboard/include/baseboard/acpi/mainboard.asl

@@ -12,4 +12,3 @@ Name(HPBA, 0xFED00000)	/* Base address of HPET table */
 /* Some global data */
 Name(OSVR, 3)	/* Assume nothing. WinXp = 1, Vista = 2, Linux = 3, WinCE = 4 */
 Name(OSV, Ones)	/* Assume nothing */
-Name(PMOD, One)	/* Assume APIC */

src/soc/amd/picasso/acpi/globalnvs.asl

@@ -1,5 +1,8 @@
 /* SPDX-License-Identifier: GPL-2.0-or-later */
 
+/* Global variables */
+Name (PMOD, Zero)	/* Interrupt Mode used by OS. Assume PIC. */
+
 /*
  * NOTE: The layout of the GNVS structure below must match the layout in
  * soc/amd/picasso/include/soc/nvs.h !!!