soc/amd/cezanne: Clear eSPI ranges before configuring eSPI

The Cezanne PSP configures the eSPI with the assumption that it's a
majolica, setting up both the serial port and the majolica EC IO decode
ranges.  Since guybrush is NOT a majolica, this doesn't work very well
there.  Clearing the decode ranges allows the guybrush platform to set
the decode ranges needed for its EC.

BUG=b:183524609
TEST=Set up eSPI on Guybrush

Signed-off-by: Martin Roth <martinroth@chromium.org>
Change-Id: I77cfb948cb9ae6d1cf001bd9e66cede8d93f50b5
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51749
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/soc/amd/cezanne/early_fch.c

@@ -68,6 +68,7 @@ void fch_early_init(void)
 		lpc_disable_spi_rom_sharing();
 
 	if (CONFIG(SOC_AMD_COMMON_BLOCK_USE_ESPI)) {
+		espi_clear_decodes();
 		espi_setup();
 		espi_configure_decodes();
 	}