KVM: x86: Drop the now unused KVM_X86_DISABLE_VALID_EXITS

Drop the KVM_X86_DISABLE_VALID_EXITS definition, as it is misleading, and
unused in KVM *because* it is misleading.  The set of exits that can be
disabled is dynamic, i.e. userspace (and KVM) must check KVM's actual
capabilities.

Suggested-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20241128013424.4096668-16-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

include/uapi/linux/kvm.h

@@ -617,10 +617,6 @@ struct kvm_ioeventfd {
 #define KVM_X86_DISABLE_EXITS_HLT            (1 << 1)
 #define KVM_X86_DISABLE_EXITS_PAUSE          (1 << 2)
 #define KVM_X86_DISABLE_EXITS_CSTATE         (1 << 3)
-#define KVM_X86_DISABLE_VALID_EXITS          (KVM_X86_DISABLE_EXITS_MWAIT | \
-                                              KVM_X86_DISABLE_EXITS_HLT | \
-                                              KVM_X86_DISABLE_EXITS_PAUSE | \
-                                              KVM_X86_DISABLE_EXITS_CSTATE)
 
 /* for KVM_ENABLE_CAP */
 struct kvm_enable_cap {