dt-bindings: interconnect: Update SLAVE_EPSS_L3_SHARED

Update the SLAVE_EPSS_L3_SHARED binding to share the same number space
as the rest of the EPSS bindings. This allows for the same provider to
be used for all of them.

Change-Id: I4e0bd80388945f7a9f897270de081d2ba87701a8
Signed-off-by: Mike Tipton <mdtipton@codeaurora.org>