powerpc/32s: Remove #ifdef CONFIG_PPC_BOOK3S_32 in head_book3s_32.S

head_book3s_32.S is only built when CONFIG_PPC_BOOK3S_32 is selected.

Remove all conditions based on CONFIG_PPC_BOOK3S_32 in the file.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/1b68632425d8866d147aea9005004e4594672211.1601975100.git.christophe.leroy@csgroup.eu