scsi: lpfc: Define lpfc_dmabuf type for ctx_buf ptr

scsi: lpfc: Define lpfc_dmabuf type for ctx_buf ptr

In LPFC_MBOXQ_t, the ctx_buf ptr shouldn't be defined as a generic void
*ptr.  It is named ctx_buf and it should only be used as an lpfc_dmabuf
*ptr.  Due to the void* declaration, there have been abuses of ctx_buf for
things not related to lpfc_dmabuf.

So, set the ptr type for *ctx_buf as lpfc_dmabuf.  Remove all type casts on
ctx_buf because it is no longer a void *ptr.  Convert the abuse of ctx_buf
for something not related to lpfc_dmabuf to use the void *context3 ptr.

A particular abuse of the ctx_buf warranted a new void *ext_buf ptr.
However, the usage of this new void *ext_buf is not generic.  It is
intended to only hold virtual addresses for extended mailbox commands.

Signed-off-by: Justin Tee <justin.tee@broadcom.com>
Link: https://lore.kernel.org/r/20240305200503.57317-10-justintee8345@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>