gpio: Make of_count_named_gpios() use new of_count_phandle_with_args()

This patch replaces the horribly coded of_count_named_gpios() with a
call to of_count_phandle_with_args() which is far more efficient. This
also changes the return value of of_gpio_count() & of_gpio_named_count()
from 'unsigned int' to 'int' so that it can return an error code. All
the users of that function are fixed up to correctly handle a negative
return value.

v2: Split GPIO portion into a separate patch

Tested-by: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Rob Herring <rob.herring@calxeda.com>
diff --git a/drivers/input/keyboard/matrix_keypad.c b/drivers/input/keyboard/matrix_keypad.c
index f4ff0dd..71d7719 100644
--- a/drivers/input/keyboard/matrix_keypad.c
+++ b/drivers/input/keyboard/matrix_keypad.c
@@ -403,7 +403,7 @@
 	struct matrix_keypad_platform_data *pdata;
 	struct device_node *np = dev->of_node;
 	unsigned int *gpios;
-	int i;
+	int i, nrow, ncol;
 
 	if (!np) {
 		dev_err(dev, "device lacks DT data\n");
@@ -416,9 +416,9 @@
 		return ERR_PTR(-ENOMEM);
 	}
 
-	pdata->num_row_gpios = of_gpio_named_count(np, "row-gpios");
-	pdata->num_col_gpios = of_gpio_named_count(np, "col-gpios");
-	if (!pdata->num_row_gpios || !pdata->num_col_gpios) {
+	pdata->num_row_gpios = nrow = of_gpio_named_count(np, "row-gpios");
+	pdata->num_col_gpios = ncol = of_gpio_named_count(np, "col-gpios");
+	if (nrow <= 0 || ncol <= 0) {
 		dev_err(dev, "number of keypad rows/columns not specified\n");
 		return ERR_PTR(-EINVAL);
 	}