config: enable ftrace features on all flavors

We enable the following function tracing options:
- FUNCTION_TRACER
- DYNAMIC_FTRACE
- FUNCTION_PROFILER
- FUNCTION_GRAPH_TRACER

With dynamic ftrace, there is very little runtime overhead.

FUNCTION_GRAPH_TRACER is disabled only on ARM because it enables
frame pointers there, so there is a real runtime cost even when it
is disabled.
config: enable SCHED_TRACER on all flavors

It doesn't have any runtime overhead except for a few KB of memory.
config: enable FTRACE_SYSCALLS on all flavor files

It incurs no runtime overhead other than a few KB of memory.
config: enable STACK_TRACER on all flavors

It carries no runtime overhead when disabled (and it is by default).
config: sync RING_BUFFER_BENCHMARK=m on s390x configs

It is enabled as a module on every other config.
config: eliminate trace flavor

With the tracing options synced to the other flavors, we can eliminate
the trace flavor entirely.

This implicitly disables the following options that used to be set
in the trace flavors:

IRQSOFF_TRACER: carries a substantial runtime overhead
MMIOTRACE: really only needed for driver development
FTRACE_SELFTEST: introduces noticible delays during boot
FTRACE_STARTUP_TEST: introduces noticible delays during tracer startup
Update arm config files: Disable Cadence network drivers

Disable ARM_AT91_ETHER in all arm config files, it is only needed on
Atmel AT91 which we don't support.

CONFIG_MACB is useful on armv6hl/default (for ARCH_PICOXCELL) and
armv7hl/default (for ARCH_ZYNQ.) Disable it in all other config files.
Update arm64 config file: Disable CONFIG_RTC_DRV_HID_SENSOR_TIME

It forcibly selects CONFIG_IIO, which we don't want.
Update arm64 config file: Disable CONFIG_IIO

It is disabled in all other non-ARM configuration files.
Update arm64 config file

I'm an idiot :-(