smpl_buf: Remove unused clk_rt variable (fixup)

Last commit removed use of the clkr_rt variable but forgot to remove the
variable itself.

Fixes: 580c48b7d5ae931b5ceb7ffa2a1ae39f89b31080
Fixes: Coverity CID 198370
Change-Id: Ida1fc5b7b338fbeb2a7c6258f36b02da93ff2186
1 file changed