soc/intel/common: Use HOST_CSR to get circular Buffer Depth

As per CSME BWG section 3.4.4.
The Circular Buffer Depth can find by checking B0:D22:F0
MMIO_HOST_CSR register.

TEST=Build and boot eve/soraka/reef/cnl-rvp

Change-Id: I1d3c09077e040b5c32b3c8be867a07f392ea4e1c
Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-on: https://review.coreboot.org/22444
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>

src/soc/intel/common/block/cse/cse.c

@@ -329,7 +329,7 @@ heci_send(const void *msg, size_t len, uint8_t host_addr, uint8_t client_addr)
 			continue;
 		}
 
-		csr = read_cse_csr();
+		csr = read_host_csr();
 		cb_size = ((csr & CSR_CBD) >> CSR_CBD_START) * SLOT_SIZE;
 		/*
 		 * Reserve one slot for the header. Limit max message