Convert CONFIG_AT91SAM9260 et al to Kconfig

This converts the following to Kconfig:
   CONFIG_AT91SAM9260
   CONFIG_AT91SAM9G20
   CONFIG_AT91SAM9XE
   CONFIG_AT91SAM9261
   CONFIG_AT91SAM9263
   CONFIG_AT91SAM9G45
   CONFIG_AT91SAM9M10G45
   CONFIG_AT91SAM9N12
   CONFIG_AT91SAM9RL
   CONFIG_AT91SAM9X5
   CONFIG_SAM9X60
   CONFIG_SAMA7G5
   CONFIG_SAMA5D2
   CONFIG_SAMA5D3
   CONFIG_SAMA5D4

These options are already select'd as needed, so we're just cleaning up
files here.

Cc: Eugen Hristev <eugen.hristev@microchip.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/at91sam9g20ek_nandflash_defconfig b/configs/at91sam9g20ek_nandflash_defconfig
index 763a5f4..4a2550b 100644
--- a/configs/at91sam9g20ek_nandflash_defconfig
+++ b/configs/at91sam9g20ek_nandflash_defconfig
@@ -15,7 +15,7 @@
 CONFIG_ENV_OFFSET_REDUND=0x100000
 CONFIG_DEBUG_UART=y
 CONFIG_SYS_LOAD_ADDR=0x22000000
-CONFIG_SYS_EXTRA_OPTIONS="AT91SAM9G20,SYS_USE_NANDFLASH"
+CONFIG_SYS_EXTRA_OPTIONS="SYS_USE_NANDFLASH"
 CONFIG_BOOTDELAY=3
 CONFIG_USE_BOOTARGS=y
 CONFIG_BOOTARGS="console=ttyS0,115200 earlyprintk mtdparts=atmel_nand:256k(bootstrap)ro,512k(uboot)ro,256k(env),256k(env_redundant),256k(spare),512k(dtb),6M(kernel)ro,-(rootfs) root=/dev/mtdblock7 rw rootfstype=jffs2"