[res] Optimize few functions for dtoh() as a noop

Given that right now our device on disk endianness is exactly
the same as the in-memory one, few functions can be optimized
into noops or raw memcpy

Bug: 319137634
Test: boot + atest libandroidfw_tests
Flag: EXEMPT performance optimization
Change-Id: I2f048feea7a93fb52434b128aa2905ebf1bb46cb