cmsis_dap: remove DAP_MAX_CLOCK

Discussed here:

    https://sourceforge.net/p/openocd/mailman/message/35466010/

Change-Id: Ic4d38a872f4b13b794ad0a8a2abdbe5bb21eced3
Signed-off-by: Adrian Negreanu <adrian.negreanu@nxp.com>
Reviewed-on: http://openocd.zylin.com/5964
Tested-by: jenkins
Reviewed-by: Bohdan Tymkiv <bhdt@cypress.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

src/jtag/drivers/cmsis_dap.c

@@ -169,10 +169,6 @@ static const char * const info_caps_str[] = {
 	"JTAG Supported"
 };
 
-/* max clock speed (kHz) */
-#define DAP_MAX_CLOCK             5000
-
-
 struct pending_transfer_result {
 	uint8_t cmd;
 	uint32_t data;
@@ -1544,9 +1540,6 @@ static int cmsis_dap_execute_queue(void)
 
 static int cmsis_dap_speed(int speed)
 {
-	if (speed > DAP_MAX_CLOCK)
-		LOG_INFO("High speed (adapter speed %d) may be limited by adapter firmware.", speed);
-
 	if (speed == 0) {
 		LOG_ERROR("RTCK not supported. Set nonzero \"adapter speed\".");
 		return ERROR_JTAG_NOT_IMPLEMENTED;