[POWERPC] Clean images in arch/powerpc/boot
[POWERPC] Clean images in arch/powerpc/boot

Add a rule to clean up the various generated image files in
arch/powerpc/boot.

Signed-off-by: Geert Uytterhoeven <205f5bcb2ea42515c4425a82ddba45c7ca0f2905@sonycom.com>
Signed-off-by: Paul Mackerras <19a0ba370c443ba08d20b5061586430ab449ee8c@samba.org>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs