mfd: mcp-core: 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
+       unsigned long flags;
+       spin_lock_irqsave(&mcp->lock, flags);

total: 0 errors, 1 warnings, 238 lines checked

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