arm: mx6: tqma6: Update to optionally configure an alternative SPI setup

By making the tqma6_iomuxc_spi() weak, this patch adds the possibility to
add a different function for this SPI configuration. This can be used
by other baseboards, that might have a different SPI setup.

This patch will be used by the upcoming WRU-IV board support which also
uses the TQMa6 SoM.

Signed-off-by: Stefan Roese <sr@denx.de>
diff --git a/board/tqc/tqma6/tqma6.c b/board/tqc/tqma6/tqma6.c
index c9e163e..29db838 100644
--- a/board/tqc/tqma6/tqma6.c
+++ b/board/tqc/tqma6/tqma6.c
@@ -145,7 +145,7 @@
 	TQMA6_SF_CS_GPIO,
 };
 
-static void tqma6_iomuxc_spi(void)
+__weak void tqma6_iomuxc_spi(void)
 {
 	unsigned i;