buildsys: minor fixes in Makefile.arch for microblaze
buildsys: minor fixes in Makefile.arch for microblaze

Do not include Makefile.commonarch directly from within arch specific
Makefile, as it is already done in parent Maefile.in.

Signed-off-by: Carmelo Amoroso <532378793705a04edd56deb76ad8c0442834d55d@st.com>

wbx-github/uclibc-ng,foss-for-synopsys-dwc-arc-processors/uClibc,groundwater/uClibc,kraj/uclibc-ng,majek/uclibc-vx32,m-labs/uclibc-lm32,brgl/uclibc-ng,hjl-tools/uClibc,brgl/uclibc-ng,atgreen/uClibc-moxie,wbx-github/uclibc-ng,m-labs/uclibc-lm32,skristiansson/uClibc-or1k,ndmsystems/uClibc,groundwater/uClibc,czankel/xtensa-uclibc,mephi42/uClibc,groundwater/uClibc,ddcc/klee-uclibc-0.9.33.2,brgl/uclibc-ng,skristiansson/uClibc-or1k,hwoarang/uClibc,wbx-github/uclibc-ng,waweber/uclibc-clang,m-labs/uclibc-lm32,wbx-github/uclibc-ng,skristiansson/uClibc-or1k,ndmsystems/uClibc,ffainelli/uClibc,waweber/uclibc-clang,hjl-tools/uClibc,hjl-tools/uClibc,ysat0/uClibc,mephi42/uClibc,majek/uclibc-vx32,kraj/uClibc,hwoarang/uClibc,ysat0/uClibc,ffainelli/uClibc,ffainelli/uClibc,foss-xtensa/uClibc,brgl/uclibc-ng,kraj/uClibc,hwoarang/uClibc,mephi42/uClibc,foss-for-synopsys-dwc-arc-processors/uClibc,groundwater/uClibc,kraj/uclibc-ng,atgreen/uClibc-moxie,ndmsystems/uClibc,czankel/xtensa-uclibc,majek/uclibc-vx32,kraj/uclibc-ng,kraj/uClibc,czankel/xtensa-uclibc,kraj/uclibc-ng,foss-for-synopsys-dwc-arc-processors/uClibc,czankel/xtensa-uclibc,hjl-tools/uClibc,foss-xtensa/uClibc,ysat0/uClibc,ffainelli/uClibc,hjl-tools/uClibc,m-labs/uclibc-lm32,hwoarang/uClibc,groundwater/uClibc,ddcc/klee-uclibc-0.9.33.2,foss-for-synopsys-dwc-arc-processors/uClibc,waweber/uclibc-clang,foss-xtensa/uClibc,mephi42/uClibc,atgreen/uClibc-moxie,kraj/uClibc,ddcc/klee-uclibc-0.9.33.2,majek/uclibc-vx32,atgreen/uClibc-moxie,ysat0/uClibc,waweber/uclibc-clang,ffainelli/uClibc,foss-xtensa/uClibc,ndmsystems/uClibc,skristiansson/uClibc-or1k,ddcc/klee-uclibc-0.9.33.2