regmap-i2c: add missing MODULE_DESCRIPTION() macro

With ARCH=arm64, make allmodconfig && make W=1 C=1 reports:
WARNING: modpost: missing MODULE_DESCRIPTION() in drivers/base/regmap/regmap-i2c.o

Add the missing invocation of the MODULE_DESCRIPTION() macro.
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Link: https://lore.kernel.org/r/20240613-md-arm64-drivers-base-regmap-v1-1-222be554d520@quicinc.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/base/regmap/regmap-i2c.c

@@ -397,4 +397,5 @@ struct regmap *__devm_regmap_init_i2c(struct i2c_client *i2c,
 }
 EXPORT_SYMBOL_GPL(__devm_regmap_init_i2c);
 
+MODULE_DESCRIPTION("Register map access API - I2C support");
 MODULE_LICENSE("GPL");