MIPS: Pistachio: Enable USB PHY driver in defconfig

Update pistachio_defconfig to enable Pistachio's USB PHY driver.
Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Cc: Kishon Vijay Abraham I <kishon@ti.com>
Cc: devicetree@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: James Hartley <james.hartley@imgtec.com>
Cc: Damien Horsley <Damien.Horsley@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/9729/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/configs/pistachio_defconfig

@@ -272,6 +272,7 @@ CONFIG_IIO=y
 CONFIG_CC10001_ADC=y
 CONFIG_PWM=y
 CONFIG_PWM_IMG=y
+CONFIG_PHY_PISTACHIO_USB=y
 CONFIG_ANDROID=y
 CONFIG_EXT4_FS=y
 CONFIG_EXT4_FS_POSIX_ACL=y