mfd: 88pm860x-core: Fix commenting and declaration spacing

Checkpatch output:

WARNING: Block comments use a trailing */ on a separate line
+        * - turn off */

WARNING: Missing a blank line after declarations
+       int ret;
+       ret = i2c_add_driver(&pm860x_driver);

total: 0 errors, 2 warnings, 1283 lines checked

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