spi: bcm2835: Unbreak the build of esoteric configs

commit 29bdedfd9cf40e59456110ca417a8cb672ac9b92 upstream.

Commit e82b0b382845 ("spi: bcm2835: Fix race on DMA termination") broke
the build with COMPILE_TEST=y on arches whose cmpxchg() requires 32-bit
operands (xtensa, older arm ISAs).

Fix by changing the dma_pending flag's type from bool to unsigned int.

Fixes: e82b0b382845 ("spi: bcm2835: Fix race on DMA termination")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: Frank Pavlic <f.pavlic@kunbus.de>
Cc: Martin Sperl <kernel@martin.sperl.org>
Cc: Noralf Trønnes <noralf@tronnes.org>
Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>