pnv/xive2: Support ESB Escalation

pnv/xive2: Support ESB Escalation

Add support for XIVE ESB Interrupt Escalation.

Suggested-by: Michael Kowal <kowal@linux.ibm.com>
[This change was taken from a patch provided by Michael Kowal.]
Signed-off-by: Glenn Miles <milesg@linux.vnet.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/20250512031100.439842-18-npiggin@gmail.com
Signed-off-by: Cédric Le Goater <clg@redhat.com>