greybus: es2: fix kernel-doc warnings

greybus: es2: fix kernel-doc warnings

Fix these kernel-doc complaints:

../drivers/greybus/es2.c:79: warning: bad line:
../drivers/greybus/es2.c:100: warning: cannot understand function prototype: 'struct es2_ap_dev '
es2.c:126: warning: Function parameter or member 'cdsi1_in_use' not described in 'es2_ap_dev'

Cc: Johan Hovold <johan@kernel.org>
Cc: Alex Elder <elder@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: greybus-dev@lists.linaro.org (moderated for non-subscribers)
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lore.kernel.org/r/20210415054338.2223-1-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>