nfc: st-nci: Remove duplicate file platform_data/st_nci.h

commit "nfc: st-nci: Rename st21nfcb to st-nci" adds
include/linux/platform_data/st_nci.h duplicated with
include/linux/platform_data/st-nci.h.

Only drivers/nfc/st-nci/i2c.c uses platform_data/st_nci.h.

Cc: stable@vger.kernel.org
Reported-by: Hauke Mehrtens <hauke@hauke-m.de>
Signed-off-by: Christophe Ricard <christophe-h.ricard@st.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>