soc/amd/common/block/lpc: Split lpc_set_spibase() into two functions

This change splits lpc_set_spibase() into two separate functions:
lpc_set_spibase() - Sets MMIO base address for SPI controller and eSPI
controller (if supported by platforms)
lpc_enable_spi_rom() - Enables SPI ROM

This split is done to allow setting of MMIO base independent of ROM
enable bits. On platforms like Picasso, eSPI base is determined by the
same register and hence eSPI can set the BAR without having to touch
the enable bits.

Signed-off-by: Furquan Shaikh <furquan@google.com>
Change-Id: I3f270ba1745b4bb8a403f00cd069a02e21d444be
Reviewed-on: https://review.coreboot.org/c/coreboot/+/41247
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

src/soc/amd/stoneyridge/southbridge.c

@@ -265,7 +265,9 @@ static uintptr_t sb_init_spi_base(void)
 	if (base)
 		return base;
 
-	lpc_set_spibase(SPI_BASE_ADDRESS, SPI_ROM_ENABLE);
+	lpc_set_spibase(SPI_BASE_ADDRESS);
+	lpc_enable_spi_rom(SPI_ROM_ENABLE);
+
 	return SPI_BASE_ADDRESS;
 }