x86/virt/tdx: Consolidate TDX global initialization states

x86/virt/tdx: Consolidate TDX global initialization states

The kernel uses several global flags to guard one-time TDX initialization
flows and prevent them from being repeated.

When the TDX module is updated, all of those states must be reset so that
the module can be initialized again. Today those states are kept as
separate global variables, which makes the reset path awkward and easy to
miss when a new state is added.

Group the states into a single structure so they can be reset together, for
example with memset(), and so a newly added state won't be missed.

Drop the __ro_after_init annotation from tdx_module_initialized because
the other two states do not have it. And with TDX module update support,
all the states need to be writable at runtime.

Signed-off-by: Chao Gao <chao.gao@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Link: https://patch.msgid.link/20260520133909.409394-4-chao.gao@intel.com