tools: .gitignore: Sort in alphabetical order

These are currently out of alphabetical order.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

tools/.gitignore

 /atmel_pmecc_params
 /bin2header
 /bmp_logo
+/common/
+/dumpimage
+/easylogo/easylogo
 /envcrc
 /fdtgrep
 /fit_check_sign
 /fit_info
+/gdb/gdbcont
+/gdb/gdbsend
 /gen_eth_addr
 /gen_ethaddr_crc
 /ifdtool
 /img2srec
 /kwboot
-/dumpimage
+/lib/
 /mips-relocs
 /mkenvimage
-/mkimage
 /mkexynosspl
-/mxsboot
+/mkimage
 /mksunxiboot
-/sunxi-spl-image-builder
+/mxsboot
 /ncb
 /proftool
 /relocate-rela
+/sunxi-spl-image-builder
 /ubsha1
 /xway-swap-bytes
-/easylogo/easylogo
-/gdb/gdbcont
-/gdb/gdbsend
-
-/lib/
-/common/