ANDROID: KVM: Allow 16 host_perm_fault handlers

Allows pKVM modules to register up to 16 handlers. The 17th registration
would end-up in a -EBUSY error. It is expected from all handlers to
return 0, unless an error occured.

Bug: 278749606
Bug: 244543039
Bug: 330669363
Change-Id: I85064d23fe67549e3f78e105b42dbf70acc063bd
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>