misc: bcm-vk: add open/release

misc: bcm-vk: add open/release

Add open/release to replace private data with context for other methods
to use.  Reason for the context is because it is allowed for multiple
sessions to open sysfs.  For each file open, when upper layer queries the
response, only those that are tied to a specified open should be returned.

Co-developed-by: Desmond Yan <desmond.yan@broadcom.com>
Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Desmond Yan <desmond.yan@broadcom.com>
Signed-off-by: Scott Branden <scott.branden@broadcom.com>
Link: https://lore.kernel.org/r/20210120175827.14820-7-scott.branden@broadcom.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>