clocksource: samsung_pwm_timer: Add support for non-DT platforms

This patch extends the driver to support platforms that still use legacy
ATAGS-based boot, without device tree, by providing an exported function
that can be used from platform code to initialize the clocksource.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
ARM: SAMSUNG: Do not register legacy timer interrupts on Exynos

This patch removes legacy PWM timer interrupt initialization from
exynos{4,5}_init_irq() functions, since it conflicts with internal
interrupt handling of the new PWM clocksource driver.

Signed-off-by: Tomasz Figa <t.figa@samsung.com>
ARM: EXYNOS: Fix support of Exynos4210 rev0 SoC

This patch extends exynos_init_time() function to handle Exynos4210 rev0
SoC, which differs in availability of system timers and needs different
clocksource initialization.

This makes it possible to use exynos_init_time() function as init_time
callback for all Exynos-based boards, including Universal_C210, which
originally had to use samsung_timer_init().

Signed-off-by: Tomasz Figa <t.figa@samsung.com>