gpu: host1x: handle the correct # of syncpt regs

BIT_WORD() truncates rather than rounds, so the loops in
syncpt_thresh_isr() and _host1x_intr_disable_all_syncpt_intrs() use <=
rather than < in an attempt to process the correct number of registers
when rounding of the conversion of count of bits to count of words is
necessary. However, when rounding isn't necessary because the value is
already a multiple of the divisor (as is the case for all values of
nb_pts the code actually sees), this causes one too many registers to
be processed.

Solve this by using and explicit DIV_ROUND_UP() call, rather than
BIT_WORD(), and comparing with < rather than <=.

Fixes: 7ede0b0b ("gpu: host1x: Add syncpoint wait and interrupts")
Cc: <stable@vger.kernel.org> # 3.10
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-By: Terje Bergstrom <tbergstrom@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>