MAINTAINERS: Include mlxreg.h in Mellanox Platform Driver files

Avoid conflicts from other subsystems by including the header with the
rest of the driver files.

Cc: Andy Shevchenko <andy@infradead.org>
Cc: Vadim Pasternak <vadimp@mellanox.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

MAINTAINERS

@@ -9711,6 +9711,7 @@ M:	Vadim Pasternak <vadimp@mellanox.com>
 L:	platform-driver-x86@vger.kernel.org
 S:	Supported
 F:	drivers/platform/mellanox/
+F:	include/linux/platform_data/mlxreg.h
 
 MELLANOX MLX4 core VPI driver
 M:	Tariq Toukan <tariqt@mellanox.com>