mmc: rockchip_sdhci: Fix 4 blocks PIO mode read limit for RK35xx

mmc: rockchip_sdhci: Fix 4 blocks PIO mode read limit for RK35xx

The commit 2cc6cde647e2 ("mmc: rockchip_sdhci: Limit number of blocks
read in a single command") introduced a limit of number of blocks to
read to fix a Data End Bit Error on RK3568 and RK3588. This had a side
affect of significant slowing down reading FIT from eMMC.

After the commit 6de9d7b2f13c ("rockchip: rk35xx: Enable eMMC HS200 mode
by default") the limit of number of blocks to read workaround is no
longer necessary and at HS200+ a Data End Bit Error is no longer
happening using PIO mode.

Change this limitation to allow reading more than 4 blocks with a single
CMD18 command in PIO mode at HS200+ speed, keep using the 4 blocks
limitation when loadig FIT from eMMC at lower speed than HS200.

Fixes: 2cc6cde647e2 ("mmc: rockchip_sdhci: Limit number of blocks read in a single command")
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Dragan Simic <dsimic@manjaro.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>