common: simplify grep pipe sed interactions

common: simplify grep pipe sed interactions

Zorro pointed out that the idiom "program | grep | sed" isn't necessary
for field extraction -- sed is perfectly capable of performing a
substitution and only printing the lines that match that substitution.
Do that for the common helpers.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Zorro Lang <zlang@redhat.com>
Signed-off-by: Zorro Lang <zlang@kernel.org>