config files: Drop incorrect comments.

There are many "force an error till we get a good number" comments in
target/board files. This refers to the use-case where a config script
sets _CPUTAPID to 0xffffffff (which presumely gets overridden later):

 if { [info exists CPUTAPID ] } {
    set _CPUTAPID $CPUTAPID
 } else {
    # Force an error until we get a good number.
    set _CPUTAPID 0xffffffff
 }

However, the same comment was also copy-pasted in many files which do
_not_ set _CPUTAPID to 0xffffffff, where the comment doesn't make any
sense at all. Drop those comments. Also, add one missing comment, and
fix small whitespace and grammar issues.

Change-Id: Ic4ba3b5ccba87ed40cea0d6a7d66609fbdfa3c71
Signed-off-by: Uwe Hermann <uwe@hermann-uwe.de>
Reviewed-on: http://openocd.zylin.com/136
Tested-by: jenkins
Reviewed-by: Peter Stuge <peter@stuge.se>

tcl/target/smp8634.cfg

@@ -15,7 +15,6 @@ if { [info exists ENDIAN] } {
 if { [info exists CPUTAPID ] } {
    set _CPUTAPID $CPUTAPID
 } else {
-   # force an error till we get a good number
    set _CPUTAPID 0x08630001
 }