microblaze: Do not select OPT_LIB_ASM by default

This option is valid only for BE systems.
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/microblaze/configs/mmu_defconfig

@@ -17,7 +17,6 @@ CONFIG_MODULE_UNLOAD=y
 # CONFIG_BLK_DEV_BSG is not set
 CONFIG_PARTITION_ADVANCED=y
 # CONFIG_EFI_PARTITION is not set
-CONFIG_OPT_LIB_ASM=y
 CONFIG_XILINX_MICROBLAZE0_USE_MSR_INSTR=1
 CONFIG_XILINX_MICROBLAZE0_USE_PCMP_INSTR=1
 CONFIG_XILINX_MICROBLAZE0_USE_BARREL=1