Move declaration of keymap_config.

Should really not declare variables in .h files - since it's included
in different .c files, a proper linker then complains that the same
variable is declared more than once (once for each .c file that the
offending .h is included in).

tmk_core/common/bootmagic.c

@@ -10,6 +10,7 @@
 #include "eeconfig.h"
 #include "bootmagic.h"
 
+keymap_config_t keymap_config;
 
 void bootmagic(void)
 {