microblaze: do not select TRACING_SUPPORT directly

Microblaze is the only architecture that selects TRACING_SUPPORT.

In my understanding, it is computed by kernel/trace/Kconfig:

  config TRACING_SUPPORT
          bool
          depends on TRACE_IRQFLAGS_SUPPORT
          depends on STACKTRACE_SUPPORT
          default y

Microblaze enables both TRACE_IRQFLAGS_SUPPORT and STACKTRACE_SUPPORT,
so there is no change in the resulted configuration.
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Link: https://lore.kernel.org/r/20201223152947.698744-1-masahiroy@kernel.orgSigned-off-by: Michal Simek <michal.simek@xilinx.com>

arch/microblaze/Kconfig

@@ -39,7 +39,6 @@ config MICROBLAZE
 	select OF_EARLY_FLATTREE
 	select PCI_DOMAINS_GENERIC if PCI
 	select PCI_SYSCALL if PCI
-	select TRACING_SUPPORT
 	select VIRT_TO_BUS
 	select CPU_NO_EFFICIENT_FFS
 	select MMU_GATHER_NO_RANGE