What changes do I need to do in UEFI settings for HS22 to support EVC
If the systems are already configured so that ESXi installs properly enabling EVC is simply a matter of turning it on and selecting the appropriate CPU baseline for the cluster under the cluster settings. There are some minimum BIOS\UEFI level requirements, hardware virtualization must be enabled for the CPU's and XD\NX bit must be enabled but I'm pretty sure these are defaults on the HS22 so you should not have to enable anything at the UEFI level to allow you to enable EVC. Depending on the choice of baseline you make you may have to power down running VM's in order to be able to configure the baseline.
Provided all ESX(i) hosts in the cluster are consistent and you know that you will not be introducing anything that predates the HS22 then you should select the "Intel® Xeon® 32nm Core™ i7" baseline. If you need to support earlier CPU's than the Xeon 5600 Westmere's that the HS22 comes with then you should select the appropriate baseline as per this VMware KB Article.