pm9g45: enable cache command

Signed-off-by: Asen Dimov <dimov@ronetix.at>

include/configs/pm9g45.h

@@ -81,6 +81,7 @@
 #undef CONFIG_CMD_FPGA
 #undef CONFIG_CMD_IMLS
 
+#define CONFIG_CMD_CACHE
 #define CONFIG_CMD_PING		1
 #define CONFIG_CMD_DHCP		1
 #define CONFIG_CMD_NAND		1