pinctrl: aspeed-g6: Add AST2600 pinconf support

The AST2600 pinconf is a little different from previous generations of
ASPEED BMC SoCs in terms of architecture. The pull-down setting is
per-pin setting now, and drive-strength support 4 kind of value (e.g.
4ma, 8ma, 12ma, 16ma).
Signed-off-by: Johnny Huang <johnny_huang@aspeedtech.com>
[AJ: Trim unused pinctrl register macros]
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Link: https://lore.kernel.org/r/20191202061432.3996-8-andrew@aj.id.auSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/aspeed/pinctrl-aspeed.h

@@ -41,6 +41,13 @@ struct aspeed_pin_config {
 	.mask = BIT_MASK(bit_) \
 }
 
+#define ASPEED_PULL_DOWN_PINCONF(pin_, reg_, bit_) \
+	ASPEED_SB_PINCONF(PIN_CONFIG_BIAS_PULL_DOWN, pin_, pin_, reg_, bit_), \
+	ASPEED_SB_PINCONF(PIN_CONFIG_BIAS_DISABLE,   pin_, pin_, reg_, bit_)
+
+#define ASPEED_PULL_UP_PINCONF(pin_, reg_, bit_) \
+	ASPEED_SB_PINCONF(PIN_CONFIG_BIAS_PULL_UP, pin_, pin_, reg_, bit_), \
+	ASPEED_SB_PINCONF(PIN_CONFIG_BIAS_DISABLE, pin_, pin_, reg_, bit_)
 /*
  * Aspeed pin configuration description.
  *