staging: rtl8188eu: core: Remove wrapper function

Remove wrapper function issue_probereq() that can be replaced by a
single line of code and rename _issue_probereq() to issue_probereq().

This patch also fixes line over 80 characters checkpatch.pl warning.

Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>