linux-user: don't adjust base of found hole

linux-user: don't adjust base of found hole

The pgb_find_hole function goes to the trouble of taking account of
both mmap_min_addr and any offset we've applied to decide the starting
address of a potential hole. This is especially important for
emulating 32bit ARM in a 32bit build as we have applied the offset to
ensure there will be space to map the ARM_COMMPAGE bellow the main
guest map (using wrapped arithmetic).

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/690
Message-Id: <20220105135009.1584676-27-alex.bennee@linaro.org>