mmc: fsl_esdhc: add pulse width detection workaround

HS400 mode on the LS1028A SoC isn't reliable. The linux driver has a
workaroung for the pulse width detection. Apply this workaround in
u-boot, too.

This will make HS400 mode work reliably on the LS1028A SoC.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>

include/fsl_esdhc.h

@@ -190,6 +190,9 @@
 #define DLL_RESET		0x40000000
 #define DLL_FREQ_SEL		0x08000000
 
+/* DLL config 1 register */
+#define DLL_PD_PULSE_STRETCH_SEL 0x80000000
+
 /* DLL status 0 register */
 #define DLL_STS_SLV_LOCK	0x08000000