byte-cntr: Don't set csr registers when read_active is false

When read_active is false, tmc-etr may be disabled. If try to access
csr registers, there will be access issue as qdss clock is disabled.
So don't set csr registers when read_active is false.

Change-Id: I2bfac6b642669a77f45e9f628c2bc68524f9d571
Signed-off-by: Mao Jinlong <jinlmao@codeaurora.org>