SPM: Modify codes to pass CI CheckPatch

Following errors/warnings are resolved:
  C99_COMMENTS: do not use C99 // comments
  CONSTANT_COMPARISON: Comparisons should place the constant on the right side
  FUNCTION_WITHOUT_ARGS: Bad function definition
  LINE_CONTINUATIONS: Avoid unnecessary line continuations
  LINE_SPACING: Missing a blank line after declarations
  LONG_LINE: line length exceeds 100 columns
  PREFER_ALIGNED: __aligned(x) is preferred over __attribute__((aligned(x)))
  PREFER_SECTION: __section(x) is preferred over __attribute__((section(x)))
  SPACING: space prohibited between function name and open parenthesis '('
  SPACING: spaces required around that '='
  TYPO_SPELLING: words misspelled

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I0ceefff582c7b70ea86b7080f763c931b758849e
diff --git a/secure_fw/spm/cmsis_func/spm_func.c b/secure_fw/spm/cmsis_func/spm_func.c
index 8f77cdb..1144b44 100644
--- a/secure_fw/spm/cmsis_func/spm_func.c
+++ b/secure_fw/spm/cmsis_func/spm_func.c
@@ -474,12 +474,12 @@
                                          const struct iovec_params_t *iovec_ptr,
                                          uint32_t excReturn)
 {
+    register uint32_t partition_idx;
     enum tfm_status_e res;
     uint32_t caller_partition_idx = desc_ptr->caller_part_idx;
     const struct spm_partition_runtime_data_t *curr_part_data;
     const struct spm_partition_runtime_data_t *caller_part_data;
     uint32_t caller_flags;
-    register uint32_t partition_idx;
     uint32_t psp;
     uint32_t partition_psp, partition_psplim;
     uint32_t partition_state;