mb/google/mancomb: Add SPI configuration to Kconfig

Mancomb will have the boot flash on a daughterboard, so the SPI speeds
need to be low for now.

BUG=b:182211161
TEST=Build

Signed-off-by: Martin Roth <martinroth@chromium.org>
Change-Id: Icacb68d65fb414197d7b8d45799527d8d2568dc7
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52741
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>

src/mainboard/google/mancomb/Kconfig

@@ -19,6 +19,7 @@ config BOARD_SPECIFIC_OPTIONS
 	select ELOG
 	select ELOG_GSMI
 	select HAVE_ACPI_RESUME
+	select HAVE_EM100_SUPPORT
 	select MAINBOARD_HAS_CHROMEOS
 	select MAINBOARD_HAS_I2C_TPM_CR50
 	select MAINBOARD_HAS_TPM2
@@ -62,6 +63,16 @@ config DRIVER_TPM_I2C_ADDR
 	hex
 	default 0x50
 
+config EFS_SPI_READ_MODE
+	int
+	default 0 if EM100 # Normal read mode
+	default 4          # Dual IO (1-2-2)
+
+config EFS_SPI_SPEED
+	int
+	default 3 if EM100 # 16.66 MHz
+	default 1          # 33.33 MHz
+
 config VARIANT_DIR
 	string
 	default "mancomb" if BOARD_GOOGLE_MANCOMB