ARM: dts: OMAP5: fix polling intervals for thermal zones

OMAP4 has a finer counter granularity, which allows for a delay of 1000ms
in the thermal zone polling intervals. OMAP5 has a different counter
mechanism, which allows at maximum a 500ms timer. Adjust the cpu thermal
zone polling interval accordingly.

Without this patch, the polling interval information is simply ignored,
and the following thermal warnings are printed during boot (assuming
thermal is enabled);

[    1.545343] ti-soc-thermal 4a0021e0.bandgap: Delay 1000 ms is not supported
[    1.552691] ti-soc-thermal 4a0021e0.bandgap: Delay 1000 ms is not supported
[    1.560029] ti-soc-thermal 4a0021e0.bandgap: Delay 1000 ms is not supported

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
Acked-by: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>