ram: stm32mp1_ddr: fix self refresh disable during DQS training

DDRCTRL_PWRCTL.SELFREF_EN needs to be reset before DQS training step, not
to enter in self refresh mode during the execution of this phase.
Depending on settings, it can be set after the DQS training.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>
Acked-by: Patrice Chotard <patrice.chotard@st.com>
diff --git a/drivers/ram/stm32mp1/stm32mp1_ddr_regs.h b/drivers/ram/stm32mp1/stm32mp1_ddr_regs.h
index 9d33186..afd93c5 100644
--- a/drivers/ram/stm32mp1/stm32mp1_ddr_regs.h
+++ b/drivers/ram/stm32mp1/stm32mp1_ddr_regs.h
@@ -260,6 +260,7 @@
 
 #define DDRCTRL_MRSTAT_MR_WR_BUSY		BIT(0)
 
+#define DDRCTRL_PWRCTL_SELFREF_EN		BIT(0)
 #define DDRCTRL_PWRCTL_POWERDOWN_EN		BIT(1)
 #define DDRCTRL_PWRCTL_SELFREF_SW		BIT(5)