AT91: at91sam9g20ek: merge 2mmc version in one board

The board-sam9g20ek-2slot-mmc.c was a revision of the at91sam9g20ek
since board revision C. It contains 2 sd/mmc slots.

This merge keep the support of the old machine ID
MACH_AT91SAM9G20EK_2MMC for backward compatibility.

Now we use the ATAG to pass the hardware functionality to kernel
with this board revision encoding
 bit 0:
     0 => 1 sd/mmc slot
     1 => 2 sd/mmc slots connectors (board from revision C)

system_rev tested on Barebox commit d8f3ee103a9f4bd

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/configs/at91sam9g20ek_defconfig

@@ -13,6 +13,7 @@ CONFIG_MODULE_UNLOAD=y
 CONFIG_ARCH_AT91=y
 CONFIG_ARCH_AT91SAM9G20=y
 CONFIG_MACH_AT91SAM9G20EK=y
+CONFIG_MACH_AT91SAM9G20EK_2MMC=y
 CONFIG_AT91_PROGRAMMABLE_CLOCKS=y
 # CONFIG_ARM_THUMB is not set
 CONFIG_AEABI=y

arch/arm/mach-at91/Kconfig

@@ -338,6 +338,7 @@ config MACH_AT91SAM9G20EK
 	  that embeds only one SD/MMC slot.
 
 config MACH_AT91SAM9G20EK_2MMC
+	depends on MACH_AT91SAM9G20EK
 	bool "Atmel AT91SAM9G20-EK Evaluation Kit with 2 SD/MMC Slots"
 	select HAVE_NAND_ATMEL_BUSWIDTH_16
 	help

arch/arm/mach-at91/Makefile

@@ -61,7 +61,6 @@ obj-$(CONFIG_MACH_AT91SAM9RLEK)	+= board-sam9rlek.o
 
 # AT91SAM9G20 board-specific support
 obj-$(CONFIG_MACH_AT91SAM9G20EK) += board-sam9g20ek.o
-obj-$(CONFIG_MACH_AT91SAM9G20EK_2MMC) += board-sam9g20ek-2slot-mmc.o
 obj-$(CONFIG_MACH_CPU9G20)	+= board-cpu9krea.o
 obj-$(CONFIG_MACH_STAMP9G20)	+= board-stamp9g20.o
 obj-$(CONFIG_MACH_PORTUXG20)	+= board-stamp9g20.o