spi/davinci: Don't select EDMA

There is no need to force selection of TI EDMA DMA engine
driver when DaVinci SPI driver is selected. The driver
builds just fine even with CONFIG_TI_EDMA disabled.

Forcing this selection causes warnings of the sort:

warning: (ARCH_KEYSTONE && SPI_DAVINCI) selects TI_EDMA which has unmet direct dependencies (DMADEVICES && (ARCH_DAVINCI || ARCH_OMAP || ARCH_KEYSTONE))

This reverts commit b5f14330.

Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Mark Brown <broonie@linaro.org>