powerpc: Rely on address instead of pte_user()

pte_user() may return 'false' when a user page is PAGE_NONE.

In that case it is still a user page and needs to be handled
as such. So use is_kernel_addr() instead.

And remove "user" text from ptdump as ptdump only dumps
kernel tables.

Note: no change done for book3s/64 which still has it
'priviledge' bit.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://msgid.link/c778dad89fad07727c31717a9c62f45357c29ebc.1695659959.git.christophe.leroy@csgroup.eu