net/qlge: Convert to SPDX license identifiers

All files related to this driver contain the following notice:

  See LICENSE.qlge for copyright and licensing details.

LICENSE.qlge can be found in
Documentation/networking/device_drivers/qlogic/. The file contains:

  - A copyright notice

    This copyright notice is redundant as all files contain the same
    copyright notice already

  - A license notice

    You may modify and redistribute the device driver code under the
    GNU General Public License (a copy of which is attached hereto as
    Exhibit A) published by the Free Software Foundation (version 2).

    This can be replaced with the corresponding SPDX license identifier
    (GPL-2.0-only) in the source files which reference this license
    file.

  - The full GPLv2 license text

    A redundant copy of LICENSES/preferred/GPL-2.0

Remove the notices and add the SPDX license identifier GPL-2.0-only to the
source files.

Finally remove the now redundant LICENSE.qlge file.

Reviewed-by: Richard Fontana <rfontana@redhat.com>
Reviewed-by: Jilayne Lovejoy <opensource@jilayne.com>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>