mfd: si476x-cmd: Remedy checkpatch style complains

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

WARNING: line over 80 characters
+                        struct si476x_rsq_status_args *rsqargs,

WARNING: line over 80 characters
+                        struct si476x_rsq_status_report *report)

WARNING: Unnecessary space before function pointer arguments
+       int (*power_up) (struct si476x_core *,

WARNING: Unnecessary space before function pointer arguments
+       int (*power_down) (struct si476x_core *,

total: 0 errors, 4 warnings, 1555 lines checked

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