media: fintek-cir: remove unused function fintek_clear_reg_bit

Found with clang:

drivers/media/rc/fintek-cir.c:55:20: warning: unused function 'fintek_clear_reg_bit' [-Wunused-function]
static inline void fintek_clear_reg_bit(struct fintek_dev *fintek, u8 val, u8 reg)

Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>