mfd: ezx-pcap: Repair coding style errors picked up with checkpatch

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

WARNING: sizeof t should be sizeof(t)
+       memset(&t, 0, sizeof t);

WARNING: void function return statements are not generally useful
+       return;
+}

total: 0 errors, 2 warnings, 542 lines checked

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