Blackfin: add a GPIO_DEFAULT_BOOT_SPI_CS

This is parallel to the existing P_DEFAULT_BOOT_SPI_CS, but in terms of
the GPIO value so it can be used with the normal gpio API.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
diff --git a/arch/blackfin/mach-bf533/include/mach/portmux.h b/arch/blackfin/mach-bf533/include/mach/portmux.h
index 075dae1..4af9195 100644
--- a/arch/blackfin/mach-bf533/include/mach/portmux.h
+++ b/arch/blackfin/mach-bf533/include/mach/portmux.h
@@ -60,6 +60,7 @@
 #define P_SPI0_SSEL2	(P_DEFINED | P_IDENT(GPIO_PF2))
 #define P_SPI0_SSEL1	(P_DEFINED | P_IDENT(GPIO_PF1))
 #define P_SPI0_SS	(P_DEFINED | P_IDENT(GPIO_PF0))
+#define GPIO_DEFAULT_BOOT_SPI_CS GPIO_PF2
 #define P_DEFAULT_BOOT_SPI_CS P_SPI0_SSEL2
 
 #define P_TMR2		(P_DONTCARE)