powerpc: Cleanup asm-prototypes.c

Last call to sys_swapcontext() from ASM was removed by
commit fbcee2eb ("powerpc/32: Always save non volatile GPRs at
syscall entry")

sys_debug_setcontext() prototype not needed anymore since
commit f3675644 ("powerpc/syscalls: signal_{32, 64} - switch
to SYSCALL_DEFINE")

sys_switch_endian() prototype not needed anymore since
commit 81dac817 ("powerpc/64: Make sys_switch_endian() traceable")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Keep _mcount() prototype to avoid modpost errors]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/3ed660a585df2080ea8412ec20fbf652f5bf013a.1646413435.git.christophe.leroy@csgroup.eu

arch/powerpc/include/asm/asm-prototypes.h

@@ -57,12 +57,7 @@ int enter_vmx_ops(void);
 void *exit_vmx_ops(void *dest);
 
 /* signals, syscalls and interrupts */
-long sys_swapcontext(struct ucontext __user *old_ctx,
-		    struct ucontext __user *new_ctx,
-		    long ctx_size);
 #ifdef CONFIG_PPC32
-long sys_debug_setcontext(struct ucontext __user *ctx,
-			  int ndbg, struct sig_dbg_op __user *dbg);
 int
 ppc_select(int n, fd_set __user *inp, fd_set __user *outp, fd_set __user *exp,
 	   struct __kernel_old_timeval __user *tvp);
@@ -81,7 +76,6 @@ unsigned long interrupt_exit_kernel_restart(struct pt_regs *regs);
 
 long ppc_fadvise64_64(int fd, int advice, u32 offset_high, u32 offset_low,
 		      u32 len_high, u32 len_low);
-long sys_switch_endian(void);
 
 /* prom_init (OpenFirmware) */
 unsigned long __init prom_init(unsigned long r3, unsigned long r4,