mmc: exynos_dw_mmc: add exynos5420 compatibles

mmc: exynos_dw_mmc: add exynos5420 compatibles

The exynos5420 DTSes in linux kernel uses the compatibles
samsung,exynos5420-dw-mshc{,-smu} instead of just
samsung,exynos-dwmmc. Match the additional compatibles in the driver
to make it possible to use it with DTSes from Linux kernel.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
[ grimler: rebase after clksel reg abstraction and re-write commit message ]
Signed-off-by: Henrik Grimler <henrik@grimler.se>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>