Fix esp RISC-V configs

[sobuch]

Seems to be broken since 6a27d9f, with the following error:

tcl//target/esp_common.cfg:69: Error: Command/target: riscv Exists
Traceback (most recent call last):
  File "tcl//target/esp32c6.cfg", line 142, in script
    create_esp_target riscv
  File "tcl//target/esp_common.cfg", line 79, in create_esp_target
    create_openocd_targets
  File "tcl//target/esp_common.cfg", line 69, in create_openocd_targets
    {target create} riscv riscv -chain-position riscv.cpu -coreid 0 -rtos hwthread

[aap-sc]

@sobuch are you sure that 6a27d9f is the right commit? Looking at the diff alone it does not look like this configuration is affected.

[aap-sc]

Looking at the diff alone it does not look like this configuration is affected.

actually... Maybe this line is to blame:

# .../riscv/startup.tcl
proc riscv {cmd args} {
	tailcall "riscv $cmd" {*}$args
}

@en-sc , given that you are the author of this specific code - could you take a look please?