uclibc: ARC: Don't mess with CPU selection

uclibc: ARC: Don't mess with CPU selection

Since uClibc-ng commit cde74b83f9b2 "ARC: remove special CFLAGS/LDFLAGS handling"
i.e. starting v1.0.23 CONFIG_ARC_CPU_xx options are not used.

Instead uClibc relies on toolchain defaults or build-system CFLAGS
for selection of ARC-specific code (i.e. distinguishes between
ARCompact and ARCv2 ISAs).

So we drop corresponding quirks from Buildroot as well.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Waldemar Brodkorb <wbx@openadk.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>