board: sl28: add SATA support

Enable SATA support. Although not supported by the usual SATA pins on
the SMARC baseboard connector, SATA mode is supported on a PCIe lane.
This way one can use a mSATA card in a Mini PCI slot.

We need to invert the received data because in this mode the polarity of
the SerDes lane is swapped. Provide a fixup in board_early_init_f() for
the SPL. board_early_init_f() is then not common between SPL and u-boot
proper anymore, thus common.c is removed, as it just contained said
function.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/board/kontron/sl28/sl28.c b/board/kontron/sl28/sl28.c
index 34f17b4..28e8c4c 100644
--- a/board/kontron/sl28/sl28.c
+++ b/board/kontron/sl28/sl28.c
@@ -19,6 +19,12 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
+int board_early_init_f(void)
+{
+	fsl_lsch3_early_init_f();
+	return 0;
+}
+
 int board_init(void)
 {
 	if (CONFIG_IS_ENABLED(FSL_CAAM))