sf: eeprom_m95xxx: set a sane default timeout

Every board currently defines this to the same value, so just default
to that to avoid having to make everyone do the same thing.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

drivers/mtd/spi/eeprom_m95xxx.c

@@ -37,6 +37,10 @@
 #define CONFIG_DEFAULT_SPI_MODE SPI_MODE_0
 #endif
 
+#ifndef CONFIG_SYS_SPI_WRITE_TOUT
+#define CONFIG_SYS_SPI_WRITE_TOUT (5 * CONFIG_SYS_HZ)
+#endif
+
 ssize_t spi_read(uchar *addr, int alen, uchar *buffer, int len)
 {
 	struct spi_slave *slave;