Drop support for Renesas H8/300 (h8300) architecture

H8/300 has been dead for several years, and the kernel for it
has not compiled for ages. Drop support for it.

Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

arch/h8300/include/asm/switch_to.h

@@ -1,50 +0,0 @@
-#ifndef _H8300_SWITCH_TO_H
-#define _H8300_SWITCH_TO_H
-
-/*
- * switch_to(n) should switch tasks to task ptr, first checking that
- * ptr isn't the current task, in which case it does nothing.  This
- * also clears the TS-flag if the task we switched to has used the
- * math co-processor latest.
- */
-/*
- * switch_to() saves the extra registers, that are not saved
- * automatically by SAVE_SWITCH_STACK in resume(), ie. d0-d5 and
- * a0-a1. Some of these are used by schedule() and its predecessors
- * and so we might get see unexpected behaviors when a task returns
- * with unexpected register values.
- *
- * syscall stores these registers itself and none of them are used
- * by syscall after the function in the syscall has been called.
- *
- * Beware that resume now expects *next to be in d1 and the offset of
- * tss to be in a1. This saves a few instructions as we no longer have
- * to push them onto the stack and read them back right after.
- *
- * 02/17/96 - Jes Sorensen (jds@kom.auc.dk)
- *
- * Changed 96/09/19 by Andreas Schwab
- * pass prev in a0, next in a1, offset of tss in d1, and whether
- * the mm structures are shared in d2 (to avoid atc flushing).
- *
- * H8/300 Porting 2002/09/04 Yoshinori Sato
- */
-
-asmlinkage void resume(void);
-#define switch_to(prev,next,last) {                         \
-  void *_last;						    \
-  __asm__ __volatile__(					    \
-  			"mov.l	%1, er0\n\t"		    \
-			"mov.l	%2, er1\n\t"		    \
-                        "mov.l  %3, er2\n\t"                \
-			"jsr @_resume\n\t"                  \
-                        "mov.l  er2,%0\n\t"                 \
-		       : "=r" (_last)			    \
-		       : "r" (&(prev->thread)),		    \
-			 "r" (&(next->thread)),		    \
-                         "g" (prev)                         \
-		       : "cc", "er0", "er1", "er2", "er3"); \
-  (last) = _last; 					    \
-}
-
-#endif /* _H8300_SWITCH_TO_H */