powerpc: Use generic fallocate compatibility syscall

The powerpc fallocate compat syscall handler is identical to the
generic implementation provided by commit 59c10c5 ("riscv:
compat: syscall: Add compat_sys_call_table implementation"), and as
such can be removed in favour of the generic implementation.

A future patch series will replace more architecture-defined syscall
handlers with generic implementations, dependent on introducing generic
implementations that are compatible with powerpc and arm's parameter
reorderings.

Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220921065605.1051927-11-rmclure@linux.ibm.com

arch/powerpc/include/asm/syscalls.h

@@ -51,8 +51,6 @@ compat_ssize_t compat_sys_readahead(int fd, u32 r4, u32 offset1, u32 offset2, u3
 int compat_sys_truncate64(const char __user *path, u32 reg4,
 			  unsigned long len1, unsigned long len2);
 
-long compat_sys_fallocate(int fd, int mode, u32 offset1, u32 offset2, u32 len1, u32 len2);
-
 int compat_sys_ftruncate64(unsigned int fd, u32 reg4, unsigned long len1,
 			   unsigned long len2);
 

arch/powerpc/include/asm/unistd.h

@@ -45,6 +45,7 @@
 #define __ARCH_WANT_SYS_UTIME
 #define __ARCH_WANT_SYS_NEWFSTATAT
 #define __ARCH_WANT_COMPAT_STAT
+#define __ARCH_WANT_COMPAT_FALLOCATE
 #define __ARCH_WANT_COMPAT_SYS_SENDFILE
 #endif
 #define __ARCH_WANT_SYS_FORK

arch/powerpc/kernel/sys_ppc32.c

@@ -79,13 +79,6 @@ int compat_sys_truncate64(const char __user * path, u32 reg4,
 	return ksys_truncate(path, merge_64(len1, len2));
 }
 
-long compat_sys_fallocate(int fd, int mode, u32 offset1, u32 offset2,
-				     u32 len1, u32 len2)
-{
-	return ksys_fallocate(fd, mode, merge_64(offset1, offset2),
-			     merge_64(len1, len2));
-}
-
 int compat_sys_ftruncate64(unsigned int fd, u32 reg4, unsigned long len1,
 				 unsigned long len2)
 {