mem: fix bug in packet access endianness changes

mem: fix bug in packet access endianness changes

The new Packet::setRaw() method incorrectly still contained
an htog() conversion.  As a result, calls to the old set()
method (now defined as setRaw(htog(v))) underwent two htog
conversions, which breaks things when htog() is not a no-op.

Interestingly the only test that caught this was a SPARC
boot test, where an IsaFake device with a non-zero return
value was getting swapped twice resulting in a register
getting loaded with 0x100000000000000 instead of 1.
(Good reason for keeping SPARC around, perhaps?)