ctr_drbg: Typo fix in the file description comment.
ctr_drbg: Typo fix in the file description comment.

Signed-off-by: Paul Sokolovsky <35cb557f011771c94f127d6fef99f804b62203f5@linaro.org>

NXPmicro/mbedtls,NXPmicro/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,NXPmicro/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,Mbed-TLS/mbedtls,ARMmbed/mbedtls,NXPmicro/mbedtls