poplar: configs: increase gunzip buffer size for the kernel

Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@linaro.org>

include/configs/poplar.h

@@ -18,7 +18,7 @@
 #define CONFIG_NR_DRAM_BANKS			2
 
 /* SYS */
-#define CONFIG_SYS_BOOTM_LEN			0x1400000
+#define CONFIG_SYS_BOOTM_LEN			SZ_64M
 #define CONFIG_SYS_INIT_SP_ADDR			0x200000
 #define CONFIG_SYS_LOAD_ADDR			0x800000
 #define CONFIG_SYS_MALLOC_LEN			SZ_32M