spi-generic.h: Adapt include guard

Rename _SPI_H_ to _SPI_GENERIC_H_ to match recent file rename.

Change-Id: I8b75e2e0a515fb540587630163ad289d0a6a0b22
Reported-by: Peter Stuge <peter@stuge.se>
Signed-off-by: Patrick Georgi <patrick@georgi-clan.de>
Reviewed-on: http://review.coreboot.org/2360
Tested-by: build bot (Jenkins)
Reviewed-by: Peter Stuge <peter@stuge.se>

src/include/spi-generic.h

@@ -21,8 +21,8 @@
  * MA 02111-1307 USA
  */
 
-#ifndef _SPI_H_
-#define _SPI_H_
+#ifndef _SPI_GENERIC_H_
+#define _SPI_GENERIC_H_
 
 #include <stdint.h>
 
@@ -201,4 +201,4 @@ static inline int spi_w8r8(struct spi_slave *slave, unsigned char byte)
 	return ret < 0 ? ret : din[1];
 }
 
-#endif	/* _SPI_H_ */
+#endif	/* _SPI_GENERIC_H_ */