tools: Add ifwitool to .gitignore
Follow up fix to the commit
56bf4f863075 ("x86: Add ifwitool for Intel Integrated Firmware Image")
in order to ignore created binary.
Cc: Simon Glass <sjg@chromium.org>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>