arch/arm/src/arm/up_cache.S: Fix cp15_invalidate_dcache. In cases where more...

arch/arm/src/arm/up_cache.S: Fix cp15_invalidate_dcache.  In cases where more than one dcache line was to be invalidated, a missing branch label would result in a false branch target into cp15_flush_idcache.  Also the .size macro was fixed for both cp15_invalidate_dcache.