hwmon: (vexpress) rename vexpress hwmon implementation

The vexpress hwmon implementation is currently just called vexpress.
This is a problem because it clashes with another module with the same
name in regulators.

This patch renames the vexpress hwmon implementation to vexpress-hwmon
so that there will be no clash in the module namespace.

Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Jean Delvare <jdelvare@suse.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: lm-sensors@lm-sensors.org
Reported-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>