build: update zpl.h for build and runtime fixes on 32-bit ARM.

See:
 https://github.com/zpl-c/zpl/pull/44
 https://github.com/zpl-c/zpl/issues/45

source/build/include/zpl.h

@@ -150,10 +150,8 @@ zpl_inline zpl_u64 zpl_rdtsc(void) {
 #if defined(__aarch64__)
     int64_t r = 0;
     asm volatile("mrs %0, cntvct_el0" : "=r"(r));
-#elif defined(__ARM_ARCH_7A__)
-    uint32_t r = 0;
-    asm volatile("mrc p15, 0, %0, c9, c13, 0" : "=r"(r));
 #elif (__ARM_ARCH >= 6)
+    uint32_t r = 0;
     uint32_t pmccntr;
     uint32_t pmuseren;
     uint32_t pmcntenset;