spi: mediatek: Fix package division error

Commit 7e963fb2 ("spi: mediatek: add ipm design support
for MT7986") makes a mistake on package dividing operation
(one change is missing), need to fix it.

Background:
Ipm design is expanding the HW capability of dma (adjust package
length from 1KB to 64KB), and using "dev_comp->ipm_support" flag
to indicate it.

Issue description:
Ipm support patch (said above) is missing to handle remainder at
package dividing operation.
One case, a transmission length is 65KB, is will divide to 1K
(package length) * 65(package loop) in non-ipm desgin case, and
will divide to 64K(package length) * 1(package loop) + 1K(remainder)
in ipm design case. And the 1K remainder will be lost with the
current SW flow, and the transmission will be failure.
So, it should be fixed.

Solution:
Add "ipm_design" flag in function "mtk_spi_get_mult_delta()" to
indicate HW capability, and modify the parameters corespondingly.

fixes: 7e963fb2

 ("spi: mediatek: add ipm design support for MT7986")
Signed-off-by: zhichao.liu <zhichao.liu@mediatek.com>
Link: https://lore.kernel.org/r/20221021091653.18297-1-zhichao.liu@mediatek.com
Signed-off-by: Mark Brown <broonie@kernel.org>