omap5: Migrate CONFIG_OMAP_PLATFORM_RESET_TIME_MAX_USEC to Kconfig

While in theory this value could be used in places outside of "omap5"
(such as OMAP4), we only make use of it today in OMAP5, so place the
Kconfig entry there.  Given that Kconfig lets us provide a default, we
drop CONFIG_DEFAULT_OMAP_RESET_TIME_MAX_USEC entirely.  The contents of
doc/README.omap-reset-time make a good help entry, so adjust them
slightly and delete the file.  Move the comment about range to where we
use the value now, and have Kconfig enforce the upper bound.

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-omap2/omap5/Kconfig b/arch/arm/mach-omap2/omap5/Kconfig
index c89c438..1a66abd 100644
--- a/arch/arm/mach-omap2/omap5/Kconfig
+++ b/arch/arm/mach-omap2/omap5/Kconfig
@@ -63,6 +63,23 @@
 	  using hardware memory firewalls. This value must be smaller than the
 	  TI_SECURE_EMIF_TOTAL_REGION_SIZE value.
 
+config OMAP_PLATFORM_RESET_TIME_MAX_USEC
+	int "Something"
+	range 0  31219
+	default 31219
+	help
+	  Most OMAPs' provide a way to specify the time for which the reset
+	  should be held low while the voltages and Oscillator outputs
+	  stabilize.
+	  This time is mostly board and PMIC dependent. Hence the boards are
+	  expected to specify a pre-computed time using the above option.
+	  This value can be computed using a summation of the below 3
+	  parameters
+	  1: Time taken by the Osciallator to stop and restart
+	  2: PMIC OTP time
+	  3: Voltage ramp time, which can be derived using the PMIC slew rate
+	     and value of voltage ramp needed.
+
 if TARGET_DRA7XX_EVM || TARGET_AM57XX_EVM
 menu "Voltage Domain OPP selections"