UPSTREAM: regulator: of: Don't flag voltage change as possible for exact voltages

UPSTREAM: regulator: of: Don't flag voltage change as possible for exact voltages

Flagging voltage changes as possible for exactly specified voltages
appears to be triggering bugs in the SDHCI code (it should be able to
handle the case where only one voltage it wants is in the range it is
allowed to set) so make sure we only set the flag in cases where there's
genuine variability.

Signed-off-by: Mark Brown <broonie@kernel.org>
(cherry picked from commit 45fa2038cf7820ecfcca8793b81e656ca3caaf0f)

Change-Id: I68c5c8fd3ca2da2ddb07af125f57158441040af3
Signed-off-by: David Wu <david.wu@rock-chips.com>