drm/xe/xe_late_bind_fw: Initialize uval variable in xe_late_bind_fw_num_fans()

drm/xe/xe_late_bind_fw: Initialize uval variable in xe_late_bind_fw_num_fans()

Initialize the uval variable to 0 in xe_late_bind_fw_num_fans() to fix
a potential use of uninitialized variable warning and ensure predictable
behavior.

The variable is passed by reference to xe_pcode_read() which should
populate it on success, but initializing it to 0 provides a safe
default value and follows kernel coding best practices.

v2:
- uval = 0 which serves as both a safe default and the fallback
  value when the pcode read operation fails.

v3:
- Handle MMIO failure (Rodrigo)
- The function should probably return the error and make the uval as
  pointer-argument, like the pcode_read.
- Change the caller of this function to propagate the error
  upwards if mmio failed.

Fixes: 45832bf9c10f3 ("drm/xe/xe_late_bind_fw: Initialize late binding firmware")
Signed-off-by: Mallesh Koujalagi <mallesh.koujalagi@intel.com>
Link: https://lore.kernel.org/r/20251002005648.3185636-1-mallesh.koujalagi@intel.com
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
(cherry picked from commit 07abc16c14693df703763c45e9fc0abfefc927d5)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>