Fixed race condition in phDal4Nfc_Write() causing same buffer to be freed twice

Adding a mutex around global variables in phDal4Nfc_Write() to
prevent a race condition when the function is called from multiple
threads. This guarantees there will only be one outstanding write
request at a time. And subsequently only one call to free() per
temporary write buffer in phDal4Nfc_DeferredCb().

Change-Id: I58420bf77e47014bd4a6455eef747118b2427758
Author: Ken Wahid <kenx.wahid@intel.com>
Signed-off-by: Ken Wahid <kenx.wahid@intel.com>
Signed-off-by: Sebastian Niciarz <sebastian.niciarz@intel.com>
Singed-off-by: Shuo Gao <shuo.gao@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
Signed-off-by: Jack Ren <jack.ren@intel.com>
Author-tracking-BZ: 41970