When running multi_v7_defconfig with CONFIG_UBSAN enabled, kernel
reports UBSAN array-index-out-of-bounds error in sunxi_mc_smp_init
function on non-sunxi platform.
Checking index to the sunxi_mc_smp_data array for out-of-bounds
condition is needed to cover non-sunxi platform. Also fix the handling
of return value from of_property_match_string function. Only negitive
value is an error condition and should bail out from the function.
Fixes: 1631090e34f5 ("ARM: sun9i: smp: Add is_a83t field")
Signed-off-by: William Zhang <william.zhang@xxxxxxxxxxxx>