Fix warnings from static analysis tools

1.STACK_USE:
    a.debug_nfcsnoop.cc: nfcsnoop_compress()
        Move buffer to heap to prevent large stack use issue.

2.FORWARD_NULL:
    a.rw_mfc.cc: rw_mfc_conn_cback()
        The null check has been added before passing a pointer variable
        to function.
    b. rw_t3t.cc : rw_t3t_conn_cback()
        Removed redundant else-if case.

3.DEADCODE:
    a. rw_mfc.cc: rw_mfc_conn_cback()
        Removed unnecessary else code as p_data cannot be NULL.

Bug: 142626701
Test: Nfc-On/Off, Tag read, HCE, CE-eSE
Change-Id: I8aaef23b80a2ea7ebf80d56cf428191255918e57
3 files changed