arm64: zynqmp: Reduce malloc memory for mini QSPI configuration

Mini U-boot runs on lower foot print of 256KB OCM. Hence 8K memory
for malloc may not be required. Reduce it by 1.5K.
Signed-off-by: NAshok Reddy Soma <ashok.reddy.soma@xilinx.com>
Signed-off-by: NMichal Simek <michal.simek@xilinx.com>

include/configs/xilinx_zynqmp_mini_qspi.h

@@ -13,6 +13,6 @@
 #include <configs/xilinx_zynqmp_mini.h>
 
 #define CONFIG_SYS_INIT_SP_ADDR	(CONFIG_SYS_TEXT_BASE + 0x20000)
-#define CONFIG_SYS_MALLOC_LEN	0x2000
+#define CONFIG_SYS_MALLOC_LEN	0x1a00
 
 #endif /* __CONFIG_ZYNQMP_MINI_QSPI_H */