arm: at91: add support for mini-box picosam9g45 board

Bootlog:
U-Boot SPL 2015.10-rc1-00452-g96a7ed1 (Aug 17 2015 - 10:32:21)
mci: setting clock 258000 Hz, block size 512
mci: setting clock 258000 Hz, block size 512
mci: setting clock 258000 Hz, block size 512
mci: setting clock 33024000 Hz, block size 512
reading u-boot.img
reading u-boot.img

U-Boot 2015.10-rc1-00452-g96a7ed1 (Aug 17 2015 - 10:32:21 +0000)

CPU: AT91SAM9G45
Crystal frequency:       12 MHz
CPU clock        :      400 MHz
Master clock     :  133.333 MHz
       Watchdog enabled
DRAM:  256 MiB
WARNING: Caches not enabled
MMC:   mci: 0
mci: setting clock 260416 Hz, block size 512
mci: setting clock 260416 Hz, block size 512
mci: setting clock 260416 Hz, block size 512
mci: setting clock 33333333 Hz, block size 512
reading uboot.env
In:    serial
Out:   serial
Err:   serial
Net:   macb0
Error: macb0 address not set.

Hit any key to stop autoboot:  0
U-Boot>

Signed-off-by: Erik van Luijk <evanluijk@interact.nl>
[add 'picosam9g45_defconfig' to MAINTAINERS]
Signed-off-by: Andreas Bießmann <andreas.devel@googlemail.com>
diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index d8d46dc..f9f148d 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -64,6 +64,11 @@
 	bool "Ronetix pm9g45 board"
 	select CPU_ARM926EJS
 
+config TARGET_PICOSAM9G45
+	bool "Mini-box picosam9g45 board"
+	select CPU_ARM926EJS
+	select SUPPORT_SPL
+
 config TARGET_AT91SAM9N12EK
 	bool "Atmel AT91SAM9N12-EK board"
 	select CPU_ARM926EJS
@@ -155,6 +160,7 @@
 source "board/esd/meesc/Kconfig"
 source "board/esd/otc570/Kconfig"
 source "board/eukrea/cpu9260/Kconfig"
+source "board/mini-box/picosam9g45/Kconfig"
 source "board/ronetix/pm9261/Kconfig"
 source "board/ronetix/pm9263/Kconfig"
 source "board/ronetix/pm9g45/Kconfig"