mmc: core: remove the invalid message in mmc_select_timing

mmc_select_hs200() and mmc_select_hs() will keep the timing
as before if switch fails. So it's meaningless to print the
failed switched mode outside based on the current host timing.

Furthermore, the original print is wrong, it should be:
pr_warn("%s: switch to %s failed\n",
	mmc_hostname(card->host),
	mmc_card_hs(card) ? "high-speed" :
	(mmc_card_hs200(card) ? "hs200" : ""));

Since we already have error message in mmc_select_hs200(),
simply remove it outside.

Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>