Code style optimization in setArgv0

Here, 15 is equal to the length of the kernel task name minus 1. Replacing 15 with a constant type improves readability, maintainability, and robustness. Although it does not directly affect performance, it can significantly reduce future maintenance costs and meet code specification requirements.

Signed-off-by: xiangshuangxi <xiangshuangxi@xiaomi.com>
(cherry picked from https://android-review.googlesource.com/q/commit:c724356019eaa1b62c74a1515e046c0fce1ed0b5)
Merged-In: I0df041c08f216fa89e987a8178d7933dca274a2a
Change-Id: I0df041c08f216fa89e987a8178d7933dca274a2a