ARM: dts: fix MMC2 regulators for Exynos5420 Arndale Octa board

Regulators for MMC2 (SD card) are PVDD_TFLASH_2V8 (LDO19) for vmmc
and PVDD_APIO_MMCOFF_2V8 (LDO13) for vqmmc.  Currently the device
tree entry for MMC2 uses PVDD_PRE_1V8 (LDO10) for vmmc and vqmmc is
not specified.  Fix it.

Without this patch:
- "mmc: dw_mmc: use mmc_regulator_get_supply to handle regulators"
  patch causes a SD card detection to fail
- "mmc: dw_mmc: Support voltage changes" patch causes a boot hang

This patch fixes both above problems.

Suggested-by: Doug Anderson <dianders@google.com>
Cc: Yuvaraj Kumar C D <yuvaraj.cd@samsung.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Acked-by: Kyungmin Park <kyungmin.park@samsung.com>
Fixes: 01730558 ("mmc: dw_mmc: Support voltage changes")
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>