Quote from the Lightroom Journal April 7 2014. Availibility of ACR 5.4.
"Camera Raw 8.4 is now available as a final release for Photoshop CS6 and Photoshop CC. This release provides new features including new preview controls, red eye correction for pets and updates to Local Corrections. In addition, this release also includes bug fixes, support for new cameras and new lenses. DNG Converter 8.4 is provided for customers using versions of Photoshop older than Photoshop CS6.
As mentioned here, updates to Camera Raw 8 for Photoshop CS6 only include new camera support, lens profile support, and bug fixes. The new features listed in the release notes are only available in Photoshop CC."
You should be able to update. More info at the link below.http://blogs.adobe.com/lightroomjournal/