drivers/spi/spi_flash.c: Add SPI vendor IDs

Currently SPI vendor IDs are magic numbers in spi_flash.c. These definitions
are needed for AMD's fch_spi. So add the definitions to spi_generic.h and use
it at spi_flash.c

BUG=b:136595978
TEST=Build test of several platforms that don't use stoneyridge. Build and boot
grunt (using stoneyridge new fch_spi).

Change-Id: Ie39485d8c092151db8c9d88afaf02e19c507c93f
Signed-off-by: Richard Spiegel <richard.spiegel@silverbackltd.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35240
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>
Reviewed-by: Martin Roth <martinroth@google.com>

src/include/spi-generic.h

@@ -28,6 +28,19 @@
 #include <stdint.h>
 #include <stddef.h>
 
+/* SPI vendor IDs */
+#define VENDOR_ID_ADESTO			0x1f
+#define VENDOR_ID_AMIC				0x37
+#define VENDOR_ID_ATMEL				0x1f
+#define VENDOR_ID_EON				0x1c
+#define VENDOR_ID_GIGADEVICE			0xc8
+#define VENDOR_ID_MACRONIX			0xc2
+#define VENDOR_ID_SPANSION			0x01
+#define VENDOR_ID_SST				0xbf
+#define VENDOR_ID_STMICRO			0x20
+#define VENDOR_ID_STMICRO_FF			0xff
+#define VENDOR_ID_WINBOND			0xef
+
 /* Controller-specific definitions: */
 
 struct spi_ctrlr;