gitignore: Add defconfig and fdtgrep

Ignore defconfig and tools/fdtgrep.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>

.gitignore

@@ -48,6 +48,7 @@
 /LOG
 /spl/
 /tpl/
+/defconfig
 
 #
 # Generated include files

tools/.gitignore

 /atmel_pmecc_params
 /bmp_logo
 /envcrc
+/fdtgrep
 /fit_check_sign
 /fit_info
 /gen_eth_addr