soc/amd/picasso/pcie_gpe: use PICM instead of PMOD in APCI code

commit 3f2467032e changed this in the APCI
code itself, but the change in the ACPI byte code generation in
pcie_gpp.c was missed and this patch fixes that.

TEST=Fixes the regression on Mandolin.

Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I60de29581296101947336f70343d6206af97e307
Reviewed-on: https://review.coreboot.org/c/coreboot/+/50207
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-by: Raul Rangel <rrangel@chromium.org>

src/soc/amd/picasso/pcie_gpp.c

@@ -127,9 +127,9 @@ static void acpigen_write_PRT(const struct device *dev)
 
 	acpigen_write_method("_PRT", 0);
 
-	/* If (PMOD) */
+	/* If (PICM) */
 	acpigen_write_if();
-	acpigen_emit_namestring("PMOD");
+	acpigen_emit_namestring("PICM");
 
 	/* Return (Package{...}) */
 	acpigen_emit_byte(RETURN_OP);
@@ -192,7 +192,7 @@ static void acpigen_write_PRT(const struct device *dev)
  *
  *         Method (_PRT, 0, NotSerialized)  // _PRT: PCI Routing Table
  *         {
- *             If (PMOD)
+ *             If (PICM)
  *             {
  *                 Return (Package (0x04)
  *                 {