powerpc: Transliterate author name and remove FIXME

The name is Mimi Phuong-Thao Vo.

Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Signed-off-by: Madhavan Srinivasan <maddy@linux.ibm.com>
Link: https://patch.msgid.link/20241110162139.5179-2-thorsten.blum@linux.dev

Author: toblux

arch/powerpc/boot/rs6000.h

@@ -1,11 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 /* IBM RS/6000 "XCOFF" file definitions for BFD.
    Copyright (C) 1990, 1991 Free Software Foundation, Inc.
-   FIXME: Can someone provide a transliteration of this name into ASCII?
-   Using the following chars caused a compiler warning on HIUX (so I replaced
-   them with octal escapes), and isn't useful without an understanding of what
-   character set it is.
-   Written by Mimi Ph\373\364ng-Th\345o V\365 of IBM
+   Written by Mimi Phuong-Thao Vo of IBM
    and John Gilmore of Cygnus Support.  */
 
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