The correct format is not used and no attempt has been made
to document the function arguments.  Makes sense to just demote
the header back down to a simple comment.

Fixes the following W=1 warnings:

 drivers/misc/ibmasm/r_heartbeat.c:49: warning: Function parameter or member 'sp' not described in 'ibmasm_start_reverse_heartbeat'
 drivers/misc/ibmasm/r_heartbeat.c:49: warning: Function parameter or member 'rhb' not described in 'ibmasm_start_reverse_heartbeat'

Cc: "Max Asböck" <amax@us.ibm.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20200701083118.45744-9-lee.jones@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>