drivers: serial: jsm: Switch "jsm" to JSM_DRIVER_NAME

This commit replaces every instance of the string "jsm"
in the driver with JSM_DRIVER_NAME, as the two are
equivalent. This should increase overall consistency.

Signed-off-by: Gavin Thomas Claugus <gclaugus@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>