platform/chrome: chromeos_tbmc - Remove unneeded const

Clang warns:

drivers/platform/chrome/chromeos_tbmc.c:102:14: warning: duplicate
'const' declaration specifier [-Wduplicate-decl-specifier]
static const SIMPLE_DEV_PM_OPS(chromeos_tbmc_pm_ops, NULL,
             ^
./include/linux/pm.h:365:56: note: expanded from macro
'SIMPLE_DEV_PM_OPS'
                                                       ^
1 warning generated.

SIMPLE_DEV_PM_OPS is already declared as const, this one is unnecessary
so remove it.

Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Benson Leung <bleung@chromium.org>