devtools: standardize script arguments

This patch modifies the arguments expected by the check-git-log script,
to match the format of arguments for the checkpatches script. Both
scripts now take certain argument options in the same format, making
them easier to use.
e.g. Both now take a commit ID range by "-r <range>"

The checkpatches help print is also updated to include the "-h" option.

The contributor's guide includes the usage of both the checkpatches and
check-git-log scripts, which needed to be updated to reflect the now
standardised format.

Signed-off-by: Ciara Power <ciara.power@intel.com>
Acked-by: Ferruh Yigit <ferruh.yigit@intel.com>
Reviewed-by: Thomas Monjalon <thomas@monjalon.net>