linux: Add uImage support for MIPS architecture

uImage support for MIPS was added in the kernel on 2013-09-03, so we
allow to build uImage for MIPS in Buildroot.

Kernel commit:
  http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=4defe4559e86e26545ab2f542656a4b966dcde53

Signed-off-by: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

linux/Config.in

@@ -168,7 +168,8 @@ choice
 config BR2_LINUX_KERNEL_UIMAGE
 	bool "uImage"
 	depends on BR2_arc || BR2_arm || BR2_armeb || BR2_bfin || \
-		   BR2_powerpc || BR2_avr32 || BR2_sh || BR2_sh64
+		   BR2_powerpc || BR2_avr32 || BR2_sh || BR2_sh64 || \
+		   BR2_mips || BR2_mipsel || BR2_mips64 || BR2_mips64el
 	select BR2_LINUX_KERNEL_UBOOT_IMAGE
 
 config BR2_LINUX_KERNEL_APPENDED_UIMAGE