art:  Few hacks to get working on TP

Need to dig into these on why it's needed

Change-Id: Ie2c2598dc5064e79e5ab5626226450b1824fe3df
art:  Update ART_USE_SMALL_NMSC to allow custom values

Updated ARM_USE_SMALL_NMSC to allow a custom value in the
boardconfig file.

EX.  ART_USE_CUSTOM_NMSC := 56 * MB