powerpc/ptdump: Fix build failure in hashpagetable.c

powerpc/ptdump: Fix build failure in hashpagetable.c

H_SUCCESS is only defined when CONFIG_PPC_PSERIES is defined.

!= H_SUCCESS means != 0. Modify the test accordingly.

Fixes: 6ed11da90749 ("powerpc/ptdump: drop non vital #ifdefs")
Cc: stable@vger.kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/795158fc1d2b3dff3bf7347881947a887ea9391a.1592227105.git.christophe.leroy@csgroup.eu