nfc: fix get_unaligned_...() misuses

* if a local variable of type uint16_t is unaligned, your compiler is FUBAR
* the whole point of get_unaligned_... is to avoid memcpy + ..._to_cpu().
  Using it *after* memcpy() (into aligned object, no less) is pointless.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>