spi: Kernel coding style fixes

Earlier commit:
"spi: Pick spi bus number from Linux idr or spi alias"
(SHA1:9b61e302)
has introduced some checkpatch issues. As pointed by
Lukas Wunner this patch does the following:
- remove whitespaces
- fix warnings, suspect code indent for conditional statements
- fix errors, code indent should use tabs
- remove spaces at the start of the line

Signed-off-by: Suniel Mahesh <sunil.m@techveda.org>
Signed-off-by: Mark Brown <broonie@kernel.org>