spi/imx: merge type SPI_IMX_VER_0_7 into SPI_IMX_VER_0_4

The only difference between SPI_IMX_VER_0_7 and SPI_IMX_VER_0_4 is
.config function.  The patch uses cpu_is_mx35 (to be removed) as the
temporary solution to consolidate functions spi_imx0_4_config and
spi_imx0_7_config into mx31_config.  As a result, type SPI_IMX_VER_0_7
can be merged into SPI_IMX_VER_0_4.

It also renames function spi_imx0_4_reset to mx31_reset to keep
consistency with other function naming.

A couple of redundant macros, MX3_CSPISTAT and MX3_CSPISTAT_RR,
together with the useless type SPI_IMX_VER_0_5 also get cleaned up.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>