ARM: tegra20: add funcmux for exposing UART over uSD slot on Tegra 20

UART-A can be exposed through uSD, this was tested on Transformer T20
but should work on all Ventana-based boards.

TX is exported on SDD pingroup corresponding to uSD CLK pin
RX is exported on SDB which is CMD pin in uSD slot

Signed-off-by: Artur Kowalski <arturkow2000@gmail.com>
Reviewed-by: Svyatoslav Ryhel <clamor95@gmail.com>
Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
diff --git a/drivers/pinctrl/tegra/funcmux-tegra20.c b/drivers/pinctrl/tegra/funcmux-tegra20.c
index 951ae19..f60d5aa 100644
--- a/drivers/pinctrl/tegra/funcmux-tegra20.c
+++ b/drivers/pinctrl/tegra/funcmux-tegra20.c
@@ -62,8 +62,15 @@
 			pinmux_tristate_disable(PMUX_PINGRP_SDIO1);
 			bad_config = 0;
 			break;
+		case FUNCMUX_UART1_SDB_SDD:
+			pinmux_set_func(PMUX_PINGRP_SDB, PMUX_FUNC_UARTA);
+			pinmux_set_func(PMUX_PINGRP_SDD, PMUX_FUNC_UARTA);
+			pinmux_tristate_disable(PMUX_PINGRP_SDB);
+			pinmux_tristate_disable(PMUX_PINGRP_SDD);
+			bad_config = 0;
+			break;
 		}
-		if (!bad_config) {
+		if (!bad_config && config != FUNCMUX_UART1_SDB_SDD) {
 			/*
 			 * Tegra appears to boot with function UARTA pre-
 			 * selected on mux group SDB. If two mux groups are