mmc: sdhci-of-aspeed: Turn down a phase correction warning

mmc: sdhci-of-aspeed: Turn down a phase correction warning

The card timing and the bus frequency are not changed atomically with
respect to calls to the set_clock() callback in the driver. The result
is the driver sees a transient state where there's a mismatch between
the two and thus the inputs to the phase correction calculation
formula are garbage.

Switch from dev_warn() to dev_dbg() to avoid noise in the normal case,
though the change does make bad configurations less likely to be
noticed.

Reported-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Reviewed-by: Joel Stanley <joel@jms.id.au>
Link: https://lore.kernel.org/r/20210607013020.85885-1-andrew@aj.id.au
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>