staging: android: logger.h: Complete documentation of logger_entry

Previously, there were simply comments after each part - Now, it is
completed properly according to "Kernel doc" Sorry in advance if I made
any mistakes.

Signed-off-by: Cruz Julian Bishop <cruzjbishop@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>