firmware: cs_dsp: Fix overflow checking of wmfw header

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

firmware: cs_dsp: Fix overflow checking of wmfw header

Fix the checking that firmware file buffer is large enough for the

wmfw header, to prevent overrunning the buffer.

The original code tested that the firmware data buffer contained

enough bytes for the sums of the size of the structs

wmfw_header + wmfw_adsp1_sizes + wmfw_footer

But wmfw_adsp1_sizes is only used on ADSP1 firmware. For ADSP2 and

Halo Core the equivalent struct is wmfw_adsp2_sizes, which is

4 bytes longer. So the length check didn't guarantee that there

are enough bytes in the firmware buffer for a header with

wmfw_adsp2_sizes.

This patch splits the length check into three separate parts. Each

of the wmfw_header, wmfw_adsp?_sizes and wmfw_footer are checked

separately before they are used.