ppc/xive2: Fix calculation of END queue sizes

ppc/xive2: Fix calculation of END queue sizes

The queue size of an Event Notification Descriptor (END)
is determined by the 'cl' and QsZ fields of the END.
If the cl field is 1, then the queue size (in bytes) will
be the size of a cache line 128B * 2^QsZ and QsZ is limited
to 4.  Otherwise, it will be 4096B * 2^QsZ with QsZ limited
to 12.

Fixes: f8a233dedf2 ("ppc/xive2: Introduce a XIVE2 core framework")
Signed-off-by: Glenn Miles <milesg@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Michael Kowal <kowal@linux.ibm.com>
Reviewed-by: Caleb Schlossin <calebs@linux.ibm.com>
Tested-by: Gautam Menghani <gautam@linux.ibm.com>
Link: https://lore.kernel.org/qemu-devel/20250512031100.439842-4-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>