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/spi/spi-oc-tiny.c b/drivers/spi/spi-oc-tiny.c
index 432e66e..cb2e284 100644
--- a/drivers/spi/spi-oc-tiny.c
+++ b/drivers/spi/spi-oc-tiny.c
@@ -54,7 +54,7 @@
 	unsigned int txc, rxc;
 	const u8 *txp;
 	u8 *rxp;
-	unsigned int gpio_cs_count;
+	int gpio_cs_count;
 	int *gpio_cs;
 };
 
@@ -74,7 +74,7 @@
 {
 	struct tiny_spi *hw = tiny_spi_to_hw(spi);
 
-	if (hw->gpio_cs_count) {
+	if (hw->gpio_cs_count > 0) {
 		gpio_set_value(hw->gpio_cs[spi->chip_select],
 			(spi->mode & SPI_CS_HIGH) ? is_active : !is_active);
 	}
@@ -254,7 +254,7 @@
 	if (!np)
 		return 0;
 	hw->gpio_cs_count = of_gpio_count(np);
-	if (hw->gpio_cs_count) {
+	if (hw->gpio_cs_count > 0) {
 		hw->gpio_cs = devm_kzalloc(&pdev->dev,
 				hw->gpio_cs_count * sizeof(unsigned int),
 				GFP_KERNEL);
@@ -352,7 +352,7 @@
 			goto exit_gpio;
 		gpio_direction_output(hw->gpio_cs[i], 1);
 	}
-	hw->bitbang.master->num_chipselect = max(1U, hw->gpio_cs_count);
+	hw->bitbang.master->num_chipselect = max(1, hw->gpio_cs_count);
 
 	/* register our spi controller */
 	err = spi_bitbang_start(&hw->bitbang);