Fix #4: remove sram.h and gpio.h from EXTRA_DIST

`sram.h` is not referenced anywhere (or, better, `grep -ir sram.h` does
not return any matching result) while `gpio.h` is included with
`<linux/gpio.h>`, suggesting the system header file is used.

devices/ccat/Makefile.am

@@ -29,10 +29,8 @@
 
 EXTRA_DIST = \
 	Kbuild.in \
-	gpio.h \
 	module.h \
 	netdev.h \
-	sram.h \
 	update.h
 
 BUILT_SOURCES = \