kernel/linux: fix packed attribute in exported headers

UBI headers (and maybe others as well) are broken because the 'packed'
attribute is not sanitised when the headers are exported to userspace.

Apply the fix from upstream:
https://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=f210735fe2f17a6225432ee3d1239bcf23a8659c

(Also, buildroot does the same, BTW)

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@anciens.enib.fr>

 # AVR32 specific configuration file

 ## select ARCH_SUPPORTS_32

 ## select ARCH_DEFAULT_32

 ## select ARCH_USE_MMU

 ## select ARCH_DEFAULT_BE

 ## select ARCH_SUPPORT_ARCH

 ## select ARCH_SUPPORT_CPU

 ## select ARCH_SUPPORT_TUNE

 ## select ARCH_SUPPORT_FPU

 ##

 ## help The AVR32 architecture, as defined by:

 ## help     http://www.atmel.com/products/avr32