msm: rng: pass correct size to kzalloc

The size passed to kzalloc should be structure size
instead of pointer size.

Signed-off-by: Yuanyuan Zhong <zyy@motorola.com>
Reviewed-on: http://gerrit.pcs.mot.com/548864
SLT-Approved: Slta Waiver <sltawvr@motorola.com>
Tested-by: Jira Key <jirakey@motorola.com>
Reviewed-by: Check Patch <CHEKPACH@motorola.com>
Reviewed-by: Klocwork kwcheck <klocwork-kwcheck@sourceforge.mot.com>
Reviewed-by: Igor Kovalenko <cik009@motorola.com>
Submit-Approved: Jira Key <jirakey@motorola.com>
Reviewed-by: Jeffrey Carlyle <jeff.carlyle@motorola.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
Build v3.12