wifi: ath10k: remove unused template structs

Currently both the wmi_bcn_tmpl_cmd and wmi_prb_tmpl_cmd structs
define:
	  u8 data[1];

Per the guidance in [1] both instances of this should be flexible
arrays. However during conversion it was discovered that neither of
these structs are actually used, so just remove them.

No functional changes, compile tested only.

[1] https://docs.kernel.org/process/deprecated.html#zero-length-and-one-element-arrays



Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://msgid.link/20231213-wmi_host_mem_chunks_flexarray-v1-4-92922d92fa2c@quicinc.com