That identity_mapped() function was loving that "1" label to the point of
completely confusing its readers.

Use named labels in each place for clarity.

No functional changes.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Link: https://lore.kernel.org/r/20240614095904.1345461-6-kirill.shutemov@linux.intel.com