mmc: fix bug in mmc_startup_v4()

The correspondence between mmc versions as used in u-boot and the version
numbers reported in register EXT_CSD_REV is wrong for versions above and
including MMC_VERSION_4_41. All those versions were shifted by one:
real 4.5 hardware appeared to be MMC_VERSION_5_0.

Fix this by adding the missing version in the correspondence table.

Reported-by: eil Eilmsteiner Heribert <eil@keba.com>
Signed-off-by: Jean-Jacques Hiblot <jjhiblot@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>