hvcs: Use dev_groups to manage hvcs device attributes

Use the dev_groups functionality to manage the attribute groups
for hvcs devices. This simplifies the code and also eliminates
errors coming from kernfs when attempting to remove a console
device that is in use.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Link: https://lore.kernel.org/r/20230203155802.404324-2-brking@linux.vnet.ibm.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>