spi/spi_sh_msiof: cosmetic clean-up

1. sort headers alphabetically
2. use fixed-size types u8, u16, u32 for register values and transferred data
3. simplify some arithmetic operations

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
[grant.likely@secretlab.ca: removed label indentation change]
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>