ARM: 6838/1: etm: fix section mismatch warning

The patch fixes the warning below:

WARNING: arch/arm/kernel/built-in.o(.data+0x27c): Section mismatch in reference from the variable etb_driver to the function .init.text:etb_probe()
The variable etb_driver references
the function __init etb_probe()
If the reference is valid then annotate the
variable with __init* or __refdata (see linux/init.h) or name the variable:
*_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console,

WARNING: arch/arm/kernel/built-in.o(.data+0x2cc): Section mismatch in reference from the variable etm_driver to the function .init.text:etm_probe()
The variable etm_driver references
the function __init etm_probe()
If the reference is valid then annotate the
variable with __init* or __refdata (see linux/init.h) or name the variable:
*_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console,

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>