spi: bcm-qspi: Add Broadcom MSPI driver

Master SPI driver for Broadcom settop, iProc SoCs. The driver
is used for devices that use SPI protocol on BRCMSTB, NSP, NS2
SoCs. SoC platform driver call exported porbe(), remove()
and suspend/resume pm_ops implemented in this common driver.

Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
Signed-off-by: Yendapally Reddy Dhananjaya Reddy
Signed-off-by: Mark Brown <broonie@kernel.org>