package/gcc: bump 9.x series to version 9.3.0

package/gcc: bump 9.x series to version 9.3.0

Remove upstream patch [1]
Rebase and rename 0002-xtensa-fix-PR-target-91880.patch
and 0003-or1k-Fix-issue-with-set_got-clobbering-LR-r9.patch

Tested using gitlab with Qemu runtime testing series [2] [3].

[1] https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=2e1e7ad18e121663082525a872f0d6fb32db4535
[2] https://gitlab.com/kubu93/buildroot/pipelines/125828238
[3] http://patchwork.ozlabs.org/project/buildroot/list/?series=159088

See:
https://gcc.gnu.org/pipermail/gcc-announce/2020/000161.html

Signed-off-by: Romain Naour <romain.naour@smile.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>