sd-as3525v2: Set LP bits in MCI_CLKENA for cards after they have been initialized.

The OF does this and while we don't have the documentation to be sure I think it's highly likely this is a low power mode referred to in one of the product "briefs".

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25936 a1c6a512-1295-4272-9138-f99709370657

firmware/target/arm/as3525/sd-as3525v2.c

@@ -562,6 +562,8 @@ static int sd_init_card(const int drive)
 
     card_info[drive].initialized = 1;
 
+    MCI_CLKENA |= 1<<(drive + 16);      /*  Set low power mode  */
+
     return 0;
 }