drm/amd/display: Fix 32-bit divide error in wait_for_alt_mode

drm/amd/display: Fix 32-bit divide error in wait_for_alt_mode

When building arm32 allyesconfig:

ld.lld: error: undefined symbol: __aeabi_uldivmod
>>> referenced by dc_link.c
>>> gpu/drm/amd/display/dc/core/dc_link.o:(wait_for_alt_mode) in archive drivers/built-in.a
>>> referenced by dc_link.c
>>> gpu/drm/amd/display/dc/core/dc_link.o:(wait_for_alt_mode) in archive drivers/built-in.a

time_taken_in_ns is of type unsigned long long so we need to use div_u64
to avoid this error.

Fixes: b5b1f4554904 ("drm/amd/display: Enable type C hotplug")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>