nvmem: imx-ocotp: Fix wrong register size

All i.MX6 SoCs have an OCOTP Controller with 4kbit fuses. The i.MX6SL is
an exception and has only 2kbit fuses.

In the TRM for the i.MX6DQ (IMX6QDRM - Rev 2, 06/2014) the fuses size is
described in chapter 46.1.1 with:
"32-bit word restricted program and read to 4Kbits of eFuse OTP(512x8)."

In the TRM for the i.MX6SL (IMX6SLRM - Rev 2, 06/2015) the fuses size is
described in chapter 34.1.1 with:
"32-bit word restricted program and read to 2 kbit of eFuse OTP(128x8)."

Since the Freescale Linux kernel OCOTP driver works with a fuses size of
2 kbit for the i.MX6SL, it looks like the TRM is wrong and the formula
to calculate the correct fuses size has to be 256x8.

Signed-off-by: Daniel Schultz <d.schultz@phytec.de>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>