rockchip: imply instead of selecting SPL_SYS_MALLOC_SIMPLE

We shouldn't force which allocator the SPL uses, since there's no
platform requirement for one over the other: in fact, we currently allow
selection of the TPL allocator but not the SPL one!

Signed-off-by: Thomas Hebb <tommyhebb@gmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 7b80630..f96841c 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1604,7 +1604,6 @@
 	select OF_CONTROL
 	select SPI
 	select SPL_DM if SPL
-	select SPL_SYS_MALLOC_SIMPLE if SPL
 	select SYS_MALLOC_F
 	select SYS_THUMB_BUILD if !ARM64
 	imply ADC
@@ -1614,6 +1613,7 @@
 	imply FAT_WRITE
 	imply SARADC_ROCKCHIP
 	imply SPL_SYSRESET
+	imply SPL_SYS_MALLOC_SIMPLE
 	imply SYS_NS16550
 	imply TPL_SYSRESET
 	imply USB_FUNCTION_FASTBOOT