sf: spi_flash cleanups

More cleanups on spi_flash side:
- Removed unneeded comments.
- Rearranged macros in proper location.
- Rearranged func declerations
- Renamed few function names.
- Added License headers.

Signed-off-by: Jagannadha Sutradharudu Teki <jaganna@xilinx.com>
5 files changed