platform/mellanox: mlxreg-hotplug: Remove unused wait.h include

The driver does not make use of anything defined in wait.h.
Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com>
[dvhart: refactor into smaller functional changes, leave spinlock.h]
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>

drivers/platform/mellanox/mlxreg-hotplug.c

@@ -42,7 +42,6 @@
 #include <linux/platform_data/mlxreg.h>
 #include <linux/platform_device.h>
 #include <linux/spinlock.h>
-#include <linux/wait.h>
 #include <linux/workqueue.h>
 
 /* Offset of event and mask registers from status register */