mmc: sdhci-of-dwcmshc: Change DLL_STRBIN_TAPNUM_DEFAULT to 0x4

mmc: sdhci-of-dwcmshc: Change DLL_STRBIN_TAPNUM_DEFAULT to 0x4

strbin signal delay under 0x8 configuration is not stable after massive
test. The recommandation of it should be 0x4.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Tested-by: Alexey Charkov <alchark@gmail.com>
Tested-by: Hugh Cole-Baker <sigmaris@gmail.com>
Fixes: 08f3dff799d4 ("mmc: sdhci-of-dwcmshc: add rockchip platform support")
Cc: stable@vger.kernel.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>