armadeus_apf9328_defconfig: bump kernel to 3.18.29

armadeus_apf9328_defconfig: bump kernel to 3.18.29

Which includes the gcc5+ fix for ftrace:

commit aeea3592a13bf12861943e44fc48f1f270941f8d
Author: Behan Webster <behanw@converseincode.com>
Date:   Wed Sep 24 01:06:46 2014 +0100

    ARM: 8158/1: LLVMLinux: use static inline in ARM ftrace.h

    With compilers which follow the C99 standard (like modern versions of gcc and
    clang), "extern inline" does the wrong thing (emits code for an externally
    linkable version of the inline function). In this case using static inline
    and removing the NULL version of return_address in return_address.c does
    the right thing.

    Signed-off-by: Behan Webster <behanw@converseincode.com>
    Reviewed-by: Mark Charlebois <charlebm@gmail.com>
    Acked-by: Steven Rostedt <rostedt@goodmis.org>
    Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Otherwise, the build dies with:

arch/arm/kernel/return_address.c:66:7: error: redefinition of ‘return_address’
 void *return_address(unsigned int level)
       ^
In file included from include/linux/ftrace.h:20:0,
                 from arch/arm/kernel/return_address.c:12:
./arch/arm/include/asm/ftrace.h:48:21: note: previous definition of ‘return_address’ was here
 extern inline void *return_address(unsigned int level)
                     ^

For more details, see:
https://travis-ci.org/buildroot/buildroot-defconfig-testing/jobs/185616889

notice: Only build tested as I don't have the hw, which is also why the
kernel is only bumped to 3.18 to make it as safe as possible.

CC: Julien Boibessot <julien.boibessot@armadeus.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>