remove 'frame' from prohibited commands list

Currently, 'frame' is prohibited on every architecture, even in gdb mode.
Since the passthrough is working on few architectures (eg. ppc64, and
vmss x86_64), so remove it from prohibited list, so that 'frame' command
can be used

This has an implication on all architectures, that 'frame' now outputs
this in default mode:

```
crash> frame
 #0  <unavailable> in ?? ()
```

instead of the before prohibited message

```
crash> frame
crash: prohibited gdb command: frame
```

Though, 'frame' should work in gdb mode for architectures that implement
'machdep->get_cpu_reg'

Cc: Sourabh Jain <[email protected]>
Cc: Hari Bathini <[email protected]>
Cc: Mahesh J Salgaonkar <[email protected]>
Cc: Naveen N. Rao <[email protected]>
Cc: Lianbo Jiang <[email protected]>
Cc: HAGIO KAZUHITO(萩尾 一仁) <[email protected]>
Cc: Tao Liu <[email protected]>
Signed-off-by: Aditya Gupta <[email protected]>

gdb_interface.c

@@ -711,7 +711,7 @@ static char *prohibited_list[] = {
 	"watch", "rwatch", "awatch", "attach", "continue", "c", "fg", "detach", 
 	"finish", "handle", "interrupt", "jump", "kill", "next", "nexti", 
 	"signal", "step", "s", "stepi", "target", "until", "delete", 
-	"clear", "disable", "enable", "condition", "ignore", "frame", "catch",
+	"clear", "disable", "enable", "condition", "ignore", "catch",
 	"tcatch", "return", "file", "exec-file", "core-file", "symbol-file",
 	"load", "si", "ni", "shell", "sy",
 	NULL  /* must be last */