ARM: uniphier: increase CONFIG_SYS_MALLOC_F_LEN for sLD3

Commit 76c52ce2 ("ARM: uniphier: increase CONFIG_SYS_MALLOC_F_LEN
to bind all nodes") missed to increase this config for sLD3.

This change is needed to add "u-boot,dm-pre-reloc" to some nodes;
more devices are bound, more malloc memory is needed.
Signed-off-by: NMasahiro Yamada <yamada.masahiro@socionext.com>

configs/uniphier_sld3_defconfig

 CONFIG_ARM=y
 CONFIG_ARCH_UNIPHIER=y
+CONFIG_SYS_MALLOC_F_LEN=0x2000
 CONFIG_ARCH_UNIPHIER_SLD3=y
 CONFIG_MICRO_SUPPORT_CARD=y
 CONFIG_SYS_TEXT_BASE=0x84000000