spi: bcm2835: Fix out-of-bounds access with more than 4 slaves

spi: bcm2835: Fix out-of-bounds access with more than 4 slaves

This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven.
This ID is fixed in Linux Kernel version v5.12.11 by commit 01415ff85a24308059e06ca3e97fd7bf75648690, it was introduced in version v5.4 by commit 571e31fa60b3697d5db26140e16d5c45c51c9815. For more details please see the references link.