net: stmmac: Correcting copyrights

Updating the open source file with correct
copyrights.

Change-Id: Iaacc8be028ac4d0368556f086c500da7d71cd109
Acked-by: Abhishek Chauhan <abchauha@qti.qualcomm.com>
Signed-off-by: Sunil Paidimarri <hisunil@codeaurora.org>