net: wwan: t7xx: Unify documentation column width

Unify the column width of the document to comply with specifications.

Signed-off-by: Jinjian Song <jinjian.song@fibocom.com>
Reviewed-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>