drm/radeon/dpm/btc: off by one in btc_set_mc_special_registers()

It should be ">=" instead of ">" here.  The table->mc_reg_address[]
array has SMC_EVERGREEN_MC_REGISTER_ARRAY_SIZE (16) elements.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org