Fix non-PIC reference in PIC for poly1305/ARMv7-NEON
* cipher/poly1305-armv7-neon.S (GET_DATA_POINTER): New. (_gcry_poly1305_armv7_neon_init_ext): Use GET_DATA_POINTER.
- Reported-by: Michael Plass <mfpnb@plass-family.net>
- Signed-off-by: Jussi Kivilinna <jussi.kivilinna@iki.fi>