[COMMON] media: mfc: DRV4.0: remove "s5p" prefix in all files.

[COMMON] media: mfc: DRV4.0: remove "s5p" prefix in all files.

The "s5p" prefix is no longer meaningful and removed.
The function and register names have been modified as shown below.

- normal function name: s5p_mfc_xxx => mfc_xxx
- static function name: mfc_xxx	=> __mfc_xxx
- register definition:   S5P_FIMV_xxx => MFC_REG_xxx
- structure name: s5p_mfc_xxx => mfc_xxx
- macro name: S5P_MFC_xxx => MFC_xxx

Change-Id: I0e8726af7c0f2d244c49e0166fcdbe1617b0a7c8
Signed-off-by: Sunyoung Kang <sy0816.kang@samsung.com>