pinctrl: Fix warning by adding missing MODULE_LICENSE

Fix below build warning

   WARNING: modpost: missing MODULE_LICENSE() in
   drivers/pinctrl/pinctrl-equilibrium.o

Introduced by commit

   1948d5c5 ("pinctrl: Add pinmux & GPIO controller driver for a new SoC")

by adding missing MODULE_LICENSE.
Signed-off-by: Rahul Tanwar <rahul.tanwar@linux.intel.com>
Link: https://lore.kernel.org/r/20191128080832.13529-2-rahul.tanwar@linux.intel.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-equilibrium.c

@@ -942,3 +942,4 @@ module_platform_driver(eqbr_pinctrl_driver);
 
 MODULE_AUTHOR("Zhu Yixin <yixin.zhu@intel.com>, Rahul Tanwar <rahul.tanwar@intel.com>");
 MODULE_DESCRIPTION("Pinctrl Driver for LGM SoC (Equilibrium)");
+MODULE_LICENSE("GPL v2");