mfd: max8925-i2c: Fix 'blank line after declarations' warning

This is part of an effort to clean-up the MFD subsystem.

WARNING: Missing a blank line after declarations
+       int ret;
+       ret = i2c_add_driver(&max8925_driver);

total: 0 errors, 1 warnings, 275 lines checked

Signed-off-by: Lee Jones <lee.jones@linaro.org>