Revert "convert SLB miss handlers to C" and subsequent commits

This reverts commits:
  5e46e29e6a ("powerpc/64s/hash: convert SLB miss handlers to C")
  8fed04d0f6 ("powerpc/64s/hash: remove user SLB data from the paca")
  655deecf67 ("powerpc/64s/hash: SLB allocation status bitmaps")
  2e1626744e ("powerpc/64s/hash: provide arch_setup_exec hooks for hash slice setup")
  89ca4e126a ("powerpc/64s/hash: Add a SLB preload cache")

This series had a few bugs, and the fixes are not all trivial. So
revert most of it for now.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/thread_info.h

@@ -29,7 +29,6 @@
 #include <asm/page.h>
 #include <asm/accounting.h>
 
-#define SLB_PRELOAD_NR	16U
 /*
  * low level task data.
  */
@@ -45,10 +44,6 @@ struct thread_info {
 #if defined(CONFIG_VIRT_CPU_ACCOUNTING_NATIVE) && defined(CONFIG_PPC32)
 	struct cpu_accounting_data accounting;
 #endif
-	u8 slb_preload_nr;
-	u8 slb_preload_tail;
-	u32 slb_preload_esid[SLB_PRELOAD_NR];
-
 	/* low level flags - has atomic operations done on it */
 	unsigned long	flags ____cacheline_aligned_in_smp;
 };
@@ -77,12 +72,6 @@ static inline struct thread_info *current_thread_info(void)
 }
 
 extern int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
-
-#ifdef CONFIG_PPC_BOOK3S_64
-void arch_setup_new_exec(void);
-#define arch_setup_new_exec arch_setup_new_exec
-#endif
-
 #endif /* __ASSEMBLY__ */
 
 /*