net: mvneta: Prevent out of bounds read in mvneta_config_rss()

In the Linux kernel, the following vulnerability has been resolved:

net: mvneta: Prevent out of bounds read in mvneta_config_rss()

The pp->indir[0] value comes from the user. It is passed to:

if (cpu_online(pp->rxq_def))

inside the mvneta_percpu_elect() function. It needs bounds checkeding

to ensure that it is not beyond the end of the cpu bitmap.