[PVFB] Fix shift key for graphical vnc display

[PVFB] Fix shift key for graphical vnc display

There is a problem in the input of the key in the VNC connection on
the PV domain. When client's keyboard is not the same as the kind of
the keyboard of PVFB and GuestOS, it is not possible to input it correctly.

This patch handled the state of shift from the set keymap. When
client's keyboard is not same as the kind of PVFB/GuestOS, it is
possible to input it correctly. It was confirmed to input it correctly
mutually with this patch between en-us and ja.

Signed-off-by: Takanori Kasai <kasai.takanori@jp.fujitsu.com>