mfd: sec-core: Fix 'missing blank line after declarations' warning

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

WARNING: Missing a blank line after declarations
+               const struct of_device_id *match;
+               match = of_match_node(sec_dt_match, i2c->dev.of_node);

total: 0 errors, 1 warnings, 494 lines checked

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