clk: msm: hdmi: fix value of constant for minimum VCO rate

Fix the value of the constant for the minimum VCO rate by
setting it to 250MHz. This fix will allow valid clock rates
such as 252MHz to be configured for the HDMI PHY and enable
certain HDMI modes to work correctly instead of failing the
validation checks when setting the VCO rate.

CRs-Fixed: 1039464
Change-Id: I0e90de49d295563aba87af39169bd3dea1f8ade7
Signed-off-by: Tatenda Chipeperekwa <tatendac@codeaurora.org>