kernel-yocto: Disable ANSI escape codes from git branch

kernel-yocto: Disable ANSI escape codes from git branch

'git branch' may use ANSI escape codes in its output (to provide colour)
which doesn't play well with commands expecting pure plain text, e.g.

    fatal: '^[[31mmaster^[[m' is not a valid branch name.

Use the --no-color option to ensure all branch names are plain text.

Cc: Bruce Ashfield <bruce.ashfield@gmail.com>
(From OE-Core rev: 87acfdb28380c26344a79a9dc0b4b403173bdc44)

Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>