rme: update boot command

In the latest FVP models, SVE support is integrated directly into the
CPU fast model. So the SVE plugin is no longer included in the model
package. Therefore, references to the SVE plugin parameters are being
removed from the documentation.

Signed-off-by: Lokesh B V <Lokesh.BV@Arm.com>
Change-Id: I6a1b0c6e694cd9d518af1e85248570b343d34521