tcmode-default.inc: use the same TUNE_PKGARCH variable as PN set in go-cross

tcmode-default.inc: use the same TUNE_PKGARCH variable as PN set in go-cross

* otherwise P_V might be set for i686 and PN and RECIPE_MAINTAINER for i586
  from bitbake -e lib32-gcc-cross-i686:

  PREFERRED_VERSION_lib32-go-cross-i686="1.12%"
  RECIPE_MAINTAINER_pn-go-cross-i586="Khem Raj <raj.khem@gmail.com>"

  $ git grep 'go-cross-${'
  meta/conf/distro/include/maintainers.inc:RECIPE_MAINTAINER_pn-go-cross-${TUNE_PKGARCH} = "Khem Raj <raj.khem@gmail.com>"
  meta/conf/distro/include/tcmode-default.inc:PREFERRED_VERSION_go-cross-${TARGET_ARCH} ?= "${GOVERSION}"
  meta/recipes-devtools/go/go-cross.inc:PN = "go-cross-${TUNE_PKGARCH}"

* actually is there a reson to use TUNE_PKGARCH here (unlike other cross/canadian-cross recipes
  which are using TARGET_ARCH/TRANSLATED_TARGET_ARCH)?

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>