[S390] Introduce user_regset accessors for s390

Add the user_regset definitions for normal and compat processes, replace
the dump_regs core dump cruft with the generic CORE_DUMP_USER_REGSET and
replace binfmt_elf32.c with the generic compat_binfmt_elf.c implementation.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
index 107e492..a79820c 100644
--- a/arch/s390/Kconfig
+++ b/arch/s390/Kconfig
@@ -146,6 +146,7 @@
 config COMPAT
 	bool "Kernel support for 31 bit emulation"
 	depends on 64BIT
+	select COMPAT_BINFMT_ELF
 	help
 	  Select this option if you want to enable your system kernel to
 	  handle system-calls from ELF binaries for 31 bit ESA.  This option