net: usb: r8152: fix "duplicate 'const' declaration specifier"

After upgrading to GCC 7.1, the duplicate const specifies in the
r8152 driver trigger the following build warnings with buildman
(observed on a 'buildman rockchip' test)::
  ../drivers/usb/eth/r8152.c:62:35: warning: duplicate 'const' declaration specifier [-Wduplicate-decl-specifier]
   static const struct r8152_version const r8152_versions[] = {
                                     ^~~~~

This commit fixes these by removing the duplicate 'const' specifier
from the declarations.
Signed-off-by: NPhilipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>
Acked-by: NJoe Hershberger <joe.hershberger@ni.com>

drivers/usb/eth/r8152.c

@@ -26,7 +26,7 @@ struct r8152_dongle {
 	unsigned short product;
 };
 
-static const struct r8152_dongle const r8152_dongles[] = {
+static const struct r8152_dongle r8152_dongles[] = {
 	/* Realtek */
 	{ 0x0bda, 0x8050 },
 	{ 0x0bda, 0x8152 },
@@ -59,7 +59,7 @@ struct r8152_version {
 	bool           gmii;
 };
 
-static const struct r8152_version const r8152_versions[] = {
+static const struct r8152_version r8152_versions[] = {
 	{ 0x4c00, RTL_VER_01, 0 },
 	{ 0x4c10, RTL_VER_02, 0 },
 	{ 0x5c00, RTL_VER_03, 1 },