lib: sbi: Fix sign-extension in sbi_misaligned_load_handler()
The misaligned load emulation does not sign-extend values correctly
due to missing sign typecast in value passed to the SET_RD() macro.
A very easy way to reproduce this issue is to load 16-bit value
0xff1e from a byte aligned address using LH instruction on hardware
lacking misaligned load/store.
This patch fixes sbi_misaligned_load_handler() for above issue.
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>