Powerpc needs flags and len to make decision on arch_get_mmap_end().

So add them as parameters to arch_get_mmap_end().
Signed-off-by: NChristophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b556daabe7d2bdb2361c4d6130280da7c1ba2c14.1649523076.git.christophe.leroy@csgroup.eu