Enable DISTRO_DEFAULTS for Rockchip platforms

This enables suitable commands needed for booting general purpose
Linux distribution. This is required for example if we want to use PXE
or DHCP as default boot targets, symbols no longer enabled by
config_distro_defaults.h .
Signed-off-by: NRomain Perier <romain.perier@collabora.com>

Kconfig

@@ -57,6 +57,7 @@ config DISTRO_DEFAULTS
 	bool "Select defaults suitable for booting general purpose Linux distributions"
 	default y if ARCH_SUNXI || TEGRA
 	default y if ARCH_LS2080A
+	default y if ARCH_ROCKCHIP
 	default n
 	select CMD_BOOTZ if ARM && !ARM64
 	select CMD_BOOTI if ARM64