powerpc/32s: Declare Hash related vars as __initdata

Hash related vars are used at init only.

Declare them in __initdata.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/3878ea30706839fcff9196790ff3f99c128c3f6a.1603348103.git.christophe.leroy@csgroup.eu