clk: qcom: Fix MSM8916 prng clock enable bit

Fix the enable bit of the pseudorandom number generator clock.

Reported-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Fixes: 3966fab8 "clk: qcom: Add MSM8916 Global Clock Controller support"
Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>