powerpc/pseries: PLPKS: undo kernel-doc comment notation

Don't use kernel-doc "/**" comment format for non-kernel-doc comments.
This prevents a kernel-doc warning:

arch/powerpc/platforms/pseries/plpks.c:186: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* Label is combination of label attributes + name.

Fixes: 2454a7af0f2a ("powerpc/pseries: define driver for Platform KeyStore")
Signed-off-by: Randy Dunlap <[e-mail]>
Reported-by: kernel test robot <[e-mail]>
Link: lore.kernel.org/r/[e-mail]
Signed-off-by: Michael Ellerman <[e-mail]>
Link: https://msgid.link/[e-mail]

arch/powerpc/platforms/pseries/plpks.c

···
 	return auth;
 }
 
-/**
+/*
  * Label is combination of label attributes + name.
  * Label attributes are used internally by kernel and not exposed to the user.
  */