soc/amd/common: Don't get eSPI address from PCI if not on x86

Exclude lpc_get_spibase() on the PSP.  This also simplifies the
espi_get_bar() function.

BUG=b:159811539
TEST=Build & boot trembyle; Verify address in PSP & x86

Signed-off-by: Martin Roth <martinroth@chromium.org>
Change-Id: I5927dd40610860b54bb35a7e5b03ddb731597745
Reviewed-on: https://review.coreboot.org/c/coreboot/+/43468
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/amd/common/block/lpc/espi_util.c b/src/soc/amd/common/block/lpc/espi_util.c
index 3750a8b..29028a4 100644
--- a/src/soc/amd/common/block/lpc/espi_util.c
+++ b/src/soc/amd/common/block/lpc/espi_util.c
@@ -19,14 +19,8 @@
 
 static uintptr_t espi_get_bar(void)
 {
-	uintptr_t espi_spi_base;
-
-	if (espi_bar)
-		return espi_bar;
-
-	espi_spi_base = lpc_get_spibase();
-	espi_update_static_bar(espi_spi_base + ESPI_OFFSET_FROM_BAR);
-
+	if (ENV_X86 && !espi_bar)
+		espi_update_static_bar(lpc_get_spibase() + ESPI_OFFSET_FROM_BAR);
 	return espi_bar;
 }