accel/qaic: remove redundant pointer pexec

Pointer pexec is being assigned a value however it is never read. The
assignment is redundant and can be removed. Replace sizeof(*pexec)
with sizeof the type and remove the declaration of pointer pexec.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Reviewed-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@quicinc.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230726140626.264952-1-colin.i.king@gmail.com