drm/pl111: Initialize clock spinlock early

The following warning is seen on systems with broken clock divider.

INFO: trying to register non-static key.
the code is fine but needs lockdep annotation.
turning off the locking correctness validator.
CPU: 0 PID: 1 Comm: swapper Not tainted 5.1.0-09698-g1fb3b52 #1
Hardware name: ARM Integrator/CP (Device Tree)
[<c0011be8>] (unwind_backtrace) from [<c000ebb8>] (show_stack+0x10/0x18)
[<c000ebb8>] (show_stack) from [<c07d3fd0>] (dump_stack+0x18/0x24)
[<c07d3fd0>] (dump_stack) from [<c0060d48>] (register_lock_class+0x674/0x6f8)
[<c0060d48>] (register_lock_class) from [<c005de2c>]
	(__lock_acquire+0x68/0x2128)
[<c005de2c>] (__lock_acquire) from [<c0060408>] (lock_acquire+0x110/0x21c)
[<c0060408>] (lock_acquire) from [<c07f755c>] (_raw_spin_lock+0x34/0x48)
[<c07f755c>] (_raw_spin_lock) from [<c0536c8c>]
	(pl111_display_enable+0xf8/0x5fc)
[<c0536c8c>] (pl111_display_enable) from [<c0502f54>]
	(drm_atomic_helper_commit_modeset_enables+0x1ec/0x244)

Since commit eedd6033 ("drm/pl111: Support variants with broken clock
divider"), the spinlock is not initialized if the clock divider is broken.
Initialize it earlier to fix the problem.

Fixes: eedd6033 ("drm/pl111: Support variants with broken clock divider")
Cc: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1557758781-23586-1-git-send-email-linux@roeck-us.net