virt: sev-guest: Replace GFP_KERNEL_ACCOUNT with GFP_KERNEL

Replace GFP_KERNEL_ACCOUNT with GFP_KERNEL in the sev-guest driver code.
GFP_KERNEL_ACCOUNT is typically used for accounting untrusted userspace
allocations. After auditing the sev-guest code, the following changes are
necessary:

  * snp_init_crypto(): Use GFP_KERNEL as this is a trusted device probe
    path.

Retain GFP_KERNEL_ACCOUNT in the following cases for robustness and
specific path requirements:

  * alloc_shared_pages(): Although all allocations are limited, retain
    GFP_KERNEL_ACCOUNT for future robustness.

  * get_report() and get_ext_report(): These functions are on the unlocked
    ioctl path and should continue using GFP_KERNEL_ACCOUNT.

Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250106124633.1418972-3-nikunj@amd.com