kernel: Correct mishandling of linux.bin for building uImage

Building uImage fails when KEEPUIMAGE is not "yes".
Remove wrong removal of linux.bin before compressing it.

(From OE-Core rev: ed5c6a0c80bac092e98f4d68dbc9cad77701bc7e)

Signed-off-by: He Zhe <zhe.he@windriver.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/kernel-uboot.bbclass

@@ -12,7 +12,6 @@ uboot_prep_kimage() {
 	${OBJCOPY} -O binary -R .note -R .comment -S "${vmlinux_path}" linux.bin
 
 	if [ "${linux_comp}" != "none" ] ; then
-		rm -f linux.bin
 		gzip -9 linux.bin
 		mv -f "linux.bin${linux_suffix}" linux.bin
 	fi