powerpc/mm: split asm/hugetlb.h into dedicated subarch files

Three subarches support hugepages:
  - fsl book3e
  - book3s/64
  - 8xx

This patch splits asm/hugetlb.h to reduce the #ifdef mess.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/include/asm/nohash/hugetlb-book3e.h

@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_POWERPC_NOHASH_HUGETLB_BOOK3E_H
+#define _ASM_POWERPC_NOHASH_HUGETLB_BOOK3E_H
+
+static inline pte_t *hugepd_page(hugepd_t hpd)
+{
+	if (WARN_ON(!hugepd_ok(hpd)))
+		return NULL;
+
+	return (pte_t *)((hpd_val(hpd) & ~HUGEPD_SHIFT_MASK) | PD_HUGE);
+}
+
+static inline unsigned int hugepd_shift(hugepd_t hpd)
+{
+	return hpd_val(hpd) & HUGEPD_SHIFT_MASK;
+}
+
+static inline pte_t *hugepte_offset(hugepd_t hpd, unsigned long addr,
+				    unsigned int pdshift)
+{
+	/*
+	 * On FSL BookE, we have multiple higher-level table entries that
+	 * point to the same hugepte.  Just use the first one since they're all
+	 * identical.  So for that case, idx=0.
+	 */
+	return hugepd_page(hpd);
+}
+
+void flush_hugetlb_page(struct vm_area_struct *vma, unsigned long vmaddr);
+
+#endif /* _ASM_POWERPC_NOHASH_HUGETLB_BOOK3E_H */