rockchip: enable SPL_SYSRESET config for all Rockchip SoCs

With Makefiles testing for $(SPL_TPL_)SYSRESET, we need SPL_SYSRESET
for do_reset() in SPL for Rockchip SoCs.

References: 87c16d49 "drivers: spl: consistently use the $(SPL_TPL_) macro"
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

arch/arm/Kconfig

@@ -1087,6 +1087,7 @@ config ARCH_ROCKCHIP
 	imply FASTBOOT
 	imply FAT_WRITE
 	imply USB_FUNCTION_FASTBOOT
+	imply SPL_SYSRESET
 
 config TARGET_THUNDERX_88XX
 	bool "Support ThunderX 88xx"