[ARM] 3517/1: move definition of PROC_INFO_SZ from procinfo.h to asm-offsets.h

Patch from Uwe Zeisberger

The symbol is only used in arch/arm/kernel/head-common.S.  This in turn
is included from arch/arm/kernel/head.S and arch/arm/kernel/head-nommu.S
which include asm-offsets.h .

Signed-off-by: Uwe Zeisberger <Uwe_Zeisberger@digi.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>