spi_bfin: use more useful GPIO labels

Use the SPI driver's name when requesting gpio lines.  When there are gpio
conflicts, this helps to narrow down the problems; "bfin-spi" is not
informative.

Signed-off-by: Bryan Wu <bryan.wu@analog.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>