KVM: x86: Consolidate flags for __linearize()

KVM: x86: Consolidate flags for __linearize()

Consolidate @write and @fetch of __linearize() into a set of flags so that
additional flags can be added without needing more/new boolean parameters,
to precisely identify the access type.

No functional change intended.

Signed-off-by: Binbin Wu <binbin.wu@linux.intel.com>
Reviewed-by: Chao Gao <chao.gao@intel.com>
Acked-by: Kai Huang <kai.huang@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
Link: https://lore.kernel.org/r/20230913124227.12574-2-binbin.wu@linux.intel.com
Signed-off-by: Sean Christopherson <seanjc@google.com>