MIPS: kernel: vpe: Make vpe_attrs an array of pointers.

Commit 567b21e9
"mips: convert vpe_class to use dev_groups"

broke the build on MIPS since vpe_attrs should be an array
of 'struct device_attribute' pointers.

Fixes the following build problem:
arch/mips/kernel/vpe.c:1372:2: error: missing braces around initializer
[-Werror=missing-braces]
arch/mips/kernel/vpe.c:1372:2: error: (near initialization for 'vpe_attrs[0]')
[-Werror=missing-braces]

Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: John Crispin <blogic@openwrt.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5819/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/vpe.c

@@ -1368,7 +1368,7 @@ static ssize_t ntcs_store(struct device *dev, struct device_attribute *attr,
 }
 static DEVICE_ATTR_RW(ntcs);
 
-static struct attribute vpe_attrs[] = {
+static struct attribute *vpe_attrs[] = {
 	&dev_attr_kill.attr,
 	&dev_attr_ntcs.attr,
 	NULL,