bsec: remove useless feature configuration API

Remove unused bsec_read/write_feature_conf() prototypes.

Change-Id: I7c99319ada288b93cea6eedf272c09f441249256
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>
Reviewed-on: https://gerrit.st.com/c/mpu/oe/st/tf-a/+/187857


Reviewed-by: CITOOLS <smet-aci-reviews@lists.codex.cro.st.com>
Reviewed-by: CIBUILD <smet-aci-builds@lists.codex.cro.st.com>
Reviewed-by: Yann GAUTIER <yann.gautier@st.com>

include/drivers/st/bsec.h

@@ -107,8 +107,6 @@ uint32_t bsec_permanent_lock_otp(uint32_t otp);
 
 uint32_t bsec_write_debug_conf(uint32_t val);
 uint32_t bsec_read_debug_conf(void);
-uint32_t bsec_write_feature_conf(uint32_t val);
-uint32_t bsec_read_feature_conf(uint32_t *val);
 
 uint32_t bsec_get_status(void);
 uint32_t bsec_get_hw_conf(void);