microblaze: Convert axi timer to DM driver

Move axi timer driver from Microblaze to generic location.
Origin implementation was irq based with counting down timer.

CONFIG_TIMER drivers are designed differently that timer is free running up
timer with automatic reload without any interrupt.
Information about clock rates are find out in timer_pre_probe() that's why
there is no need to get any additional information from DT in the driver
itself (only register offset).

Signed-off-by: Michal Simek <michal.simek@amd.com>
Tested-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Link: https://lore.kernel.org/r/6c12fc86bbc1f17d05c25018862e7b7b03346b36.1654684731.git.michal.simek@amd.com
diff --git a/drivers/timer/Kconfig b/drivers/timer/Kconfig
index 7b8ab56..44d1a81 100644
--- a/drivers/timer/Kconfig
+++ b/drivers/timer/Kconfig
@@ -272,4 +272,12 @@
 	  Select this to enable support for the timer found on
 	  NXP i.MX devices.
 
+config XILINX_TIMER
+	bool "Xilinx timer support"
+	depends on TIMER
+	select REGMAP
+	help
+	  Select this to enable support for the timer found on
+	  any Xilinx boards (axi timer).
+
 endmenu