spi/topcliff: cleanups for style and conciseness

This patch makes multiple cleanups to the new topcliff pch spi driver
including, but not limited to,
- removing superfluous brackets around variables
- open coding functions that are only used once
- removing unnecessary line breaks
- removing unused functions
- simplifying the interrupt enable/disable code
- remove unnecessary (void *) casts.
- remove b_mem_fail from pch_spi_set_tx to code it more cleanly
- shorten dev_dbg() messages for conciseness and readability

More cleanups are still needed in this driver.  In particular,
- the driver filename should be changed to spi_topcliff_pch.c
- many of the dev_dbg() lines should be trimmed (particularly the ones
  on unconditional code paths).
- I suspect that the locking model not correct.  I'd like to know what
  drivers' critical regions are, and how they are protected.
- get_resources and release_resources probably should be open coded in
  .probe and .release respectively.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>