KVM: x86/mmu: Make is_nx_huge_page_enabled an inline function

mainline inclusion
from mainline-v5.14-rc1
commit a9d6496d
category: feature
bugzilla: https://gitee.com/openeuler/intel-kernel/issues/I7S3VQ
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a9d6496d667fdb86713868a402378a0e4db62b50



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Function 'is_nx_huge_page_enabled' is called only by kvm/mmu, so make
it as inline fucntion and remove the unnecessary declaration.

Cc: Ben Gardon <bgardon@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Message-Id: <1622102271-63107-1-git-send-email-zhangshaokun@hisilicon.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>