If we grep the patch file it will contain some weird email encoding
when processing utf-8 strings. Eg:

Subject: [PATCH v2 1/1] =?utf-8?q?media=3A_v4l2-core=3A_Replace_the_check_fo?=
        =?utf-8?q?r_firmware_registered_I=C2=B2C_devices?=

Let git log do the hard work for us.

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>