powerpc/powermac: Add additional missing lockdep_register_key()

Commit df1f679d ("powerpc/powermac: Add missing
lockdep_register_key()") fixed a problem that was causing a WARNING.

There are two other places in the same file with the same problem
originating from commit 9e607f72 ("i2c_powermac: shut up lockdep
warning").

Add missing lockdep_register_key()

Fixes: 9e607f72

 ("i2c_powermac: shut up lockdep warning")
Reported-by: Erhard Furtner <erhard_f@mailbox.org>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Depends-on: df1f679d

 ("powerpc/powermac: Add missing lockdep_register_key()")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=200055
Link: https://lore.kernel.org/r/2c7e421874e21b2fb87813d768cf662f630c2ad4.1638984999.git.christophe.leroy@csgroup.eu