configs: phycore_am62x_r5_defconfig: Increase SPL Malloc Pool

Increase the malloc pool size for the SPL by additional 4kB from
0x7000 to 0x8000.

This fixes following error message:
  ...
  alloc space exhausted ptr 7028 limit 7000
  DRAM init failed: -12

Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
diff --git a/configs/phycore_am62x_r5_defconfig b/configs/phycore_am62x_r5_defconfig
index a856e69..c5ddcd7 100644
--- a/configs/phycore_am62x_r5_defconfig
+++ b/configs/phycore_am62x_r5_defconfig
@@ -21,7 +21,7 @@
 CONFIG_SPL_SERIAL=y
 CONFIG_SPL_DRIVERS_MISC=y
 CONFIG_SPL_STACK_R_ADDR=0x82000000
-CONFIG_SPL_SYS_MALLOC_F_LEN=0x7000
+CONFIG_SPL_SYS_MALLOC_F_LEN=0x8000
 CONFIG_SPL_TEXT_BASE=0x43c00000
 CONFIG_SPL_HAS_BSS_LINKER_SECTION=y
 CONFIG_SPL_BSS_START_ADDR=0x43c3b000