microblaze: remove OUTPUT_FORMAT from linker script

OUTPUT_FORMAT setup bigendian platform. Microblaze Linux port
is becoming bi endian that's why it is removed.
Signed-off-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/kernel/vmlinux.lds.S

@@ -8,7 +8,6 @@
  * for more details.
  */
 
-OUTPUT_FORMAT("elf32-microblaze", "elf32-microblaze", "elf32-microblaze")
 OUTPUT_ARCH(microblaze)
 ENTRY(microblaze_start)